Variable power optical system, optical apparatus, and variable power optical system manufacturing method

ABSTRACT

A variable magnification optical system includes: a first lens group (G 1 ) having a negative refractive power; a second lens group (G 2 ) having a positive refractive power; an intermediate group (Gn) disposed closer to an image side than the second lens group (G 2 ); and a vibration-reduction lens group (VR) disposed closer to the image side than the intermediate group (Gn) and configured to be movable so as to have a component in a direction orthogonal to an optical axis. The system performs varying magnification by changing at least the distance between the first lens group (G 1 ) and the second lens group (G 2 ) and the distance between the second lens group (G 2 ) and the intermediate group (Gn), and the system satisfies Conditional Expression (1). 
       1.500&lt;β( Gn ) t&lt;100.000    (1)
         where   β(Gn)t: an imaging magnification of the intermediate group (Gn) in a telephoto end state

TECHNICAL FIELD

The present invention relates to a variable magnification opticalsystem, an optical apparatus, and a method for manufacturing thevariable magnification optical system.

Priority is claimed on Japanese Patent Application No. 2015-017917,filed Jan. 30, 2015, the content of which is incorporated herein byreference.

TECHNICAL BACKGROUND

Conventionally, a variable magnification optical system having a wideangle of view including a camera shake compensation mechanism has beenproposed (for example, see Patent Document 1).

RELATED ART DOCUMENTS Patent Document Patent Document 1:

Japanese Patent Application, Publication No. H11-231220

SUMMARY OF INVENTION Technical Problem

In recent years, there has been increasing demand for a variablemagnification optical system which has a satisfactory opticalperformance and has a brighter F-value.

Solution to Problem

According to an aspect of the present invention, there is provided avariable magnification optical system including: a first lens grouphaving a negative refractive power; a second lens group having apositive refractive power; an intermediate group disposed closer to animage side than the second lens group; and a vibration-reduction lensgroup disposed closer to the image side than the intermediate group andconfigured to be movable so as to have a component in a directionorthogonal to an optical axis, wherein the system performs varyingmagnification by changing at least the distance between the first lensgroup and the second lens group and the distance between the second lensgroup and the intermediate group, and the system satisfies the followingconditional expression.

1.500<β(Gn)t<100.000

where

β(Gn)t: an imaging magnification of the n-th lens group in a telephotoend state

According to another aspect of the present invention, there is provideda variable magnification optical system including, in order from anobject: a first lens group having a negative refractive power; a secondlens group having a positive refractive power, the first and second lensgroups; an n-th lens group which is disposed closer to the image sidethan the second lens group, of which the position in the directionorthogonal to an optical axis is fixed, and which has negativerefractive power; and a vibration-reduction lens group disposed closerto the image side than the n-th lens group and configured to be movableso as to have a component in the direction orthogonal to the opticalaxis, wherein the system performs varying magnification by changing atleast the distance between the first lens group and the second lensgroup and the distance between the second lens group and the n-th lensgroup, and the system satisfies the following conditional expression.

1.500<β(Gn)t<100.000

where

β(Gn)t: an imaging magnification of the intermediate group in atelephoto end state

According to another aspect of the present invention, there is providedan optical apparatus having the above-described variable magnificationoptical system mounted thereon.

According to another aspect of the present invention, there is provideda method for manufacturing a variable magnification optical system,wherein the variable magnification optical system includes: a first lensgroup having a negative refractive power; a second lens group having apositive refractive power; an intermediate group disposed closer to animage side than the second lens group; and a vibration-reduction lensgroup disposed closer to the image side than the intermediate group andconfigured to be movable so as to have a component in a directionorthogonal to an optical axis, wherein the system performs varyingmagnification by changing at least the distance between the first lensgroup and the second lens group and the distance between the second lensgroup and the intermediate group, and wherein the method includesarranging the respective lenses in a lens barrel so as to satisfy thefollowing conditional expression.

1.500<β(Gn)t<100.000

where

β(Gn)t: an imaging magnification of the intermediate group in atelephoto end state

According to another aspect of the present invention, there is provideda method for manufacturing a variable magnification optical system,wherein the variable magnification optical system includes, in orderfrom an object: a first lens group having a negative refractive power; asecond lens group having a positive refractive power, the first andsecond lens groups; an n-th lens group which is disposed closer to theimage side than the second lens group, of which the position in thedirection orthogonal to an optical axis is fixed, and which has negativerefractive power; and a vibration-reduction lens group disposed closerto the image side than the n-th lens group and configured to be movableso as to have a component in the direction orthogonal to the opticalaxis, wherein the system performs varying magnification by changing atleast the distance between the first lens group and the second lensgroup and the distance between the second lens group and the n-th lensgroup, and wherein the method includes arranging the respective lensgroups in a lens barrel so as to satisfy the following conditionalexpression.

1.500<β(Gn)t<100.000

where

β(Gn)t: an imaging magnification of the intermediate group in atelephoto end state

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a variable magnification opticalsystem according to Example 1, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 2 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 1 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 3 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 1 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 4 is a cross-sectional view of a variable magnification opticalsystem according to Example 2, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 5 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 2 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 6 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 2 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 7 is a cross-sectional view of a variable magnification opticalsystem according to Example 3, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 8 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 3 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 9 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 3 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 10 is a cross-sectional view of a variable magnification opticalsystem according to Example 4, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 11 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 4 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 12 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 4 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 13 is a cross-sectional view of a variable magnification opticalsystem according to Example 5, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 14 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 5 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 15 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 5 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 16 is a cross-sectional view of a variable magnification opticalsystem according to Example 6, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 17 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 6 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 18 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 6 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 19 is a cross-sectional view of a variable magnification opticalsystem according to Example 7, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 20 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 7 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 21 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 7 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 22 is a cross-sectional view of a variable magnification opticalsystem according to Example 8, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 23 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 8 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 24 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 8 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 25 is a cross-sectional view of a variable magnification opticalsystem according to Example 9, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 26 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 9 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 27 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 9 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 28 is a cross-sectional view of a variable magnification opticalsystem according to Example 10, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 29 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 10 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 30 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 10 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 31 is a cross-sectional views of a variable magnification opticalsystem according to Example 11, wherein parts (W), (M), and (T) are in awide-angle end state, an intermediate focal length state, and atelephoto end state, respectively.

FIG. 32 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 11 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 33 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 11 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 34 is a cross-sectional view of a variable magnification opticalsystem according to Example 12 in a wide-angle end state, anintermediate focal length state, and a telephoto end state,respectively.

FIG. 35 shows graphs illustrating various aberrations of the variablemagnification optical system according to Example 12 upon focusing oninfinity, wherein parts (a), (b), and (c) are in the wide-angle endstate, the intermediate focal length state, and the telephoto end state,respectively.

FIG. 36 shows graphs illustrating lateral aberrations of the variablemagnification optical system according to Example 12 after image blurcorrection was performed upon focusing on infinity, wherein parts (a),(b), and (c) are in the wide-angle end state, the intermediate focallength state, and the telephoto end state, respectively.

FIG. 37 is a diagram illustrating an example of a configuration of acamera having a variable magnification optical system mounted thereon.

FIG. 38 is a diagram illustrating an outline of an example of a methodfor manufacturing a variable magnification optical system.

DESCRIPTION OF EMBODIMENTS

An embodiment will now be described with reference to the drawings. FIG.1 illustrates an example of a configuration of a variable magnificationoptical system (variable power optical system) ZL. In other examples,the number of lens groups, a lens configuration of each lens group, andthe like can be changed appropriately.

In an embodiment, a variable magnification optical system ZL includes afirst lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, and an intermediate group(an n-th lens group) disposed closer to an image side than the secondlens group G2, the system including a vibration-reduction lens group VRdisposed closer to the image side than the intermediate group Gn andconfigured to be moveable so as to have component in a directionorthogonal to an optical axis, the system performing varyingmagnification (varying power) by changing at least the distance betweenthe first lens group G1 and the second lens group G2 and the distancebetween the second lens group G2 and the intermediate group Gn. In anexample, the position of the intermediate group Gn in the directionorthogonal to the optical axis is immovable, and the intermediate groupGn has a negative refractive power.

In Example 1 illustrated in FIG. 1, the intermediate group Gn of whichthe position in the direction orthogonal to the optical axis isimmovable and which has negative refractive power and thevibration-reduction lens group VR disposed at an image-side of theintermediate group correspond to a 31st lens group G31 and a 32nd lensgroup G32, respectively. In Examples 2, 3, 5, and 7 to 11 to bedescribed later, the intermediate group Gn and the vibration-reductionlens group VR disposed at an image-side of the intermediate groupcorrespond to a 31st lens group G31 and a 32nd lens group G32,respectively. In Examples 4, 6, and 12, the intermediate group Gn andthe vibration-reduction lens group VR disposed at an image-side of theintermediate group correspond to a fourth lens group G4 and a fifth lensgroup G5.

The vibration-reduction lens group VR preferably has negative refractivepower.

As described above, the variable magnification optical system ZL haslens groups having negative, positive, negative, and positive refractivepower or negative, positive, negative, positive, and positive refractivepower and changes at least the distances between these lens groups.Therefore, it is possible to implement a variable magnification opticalsystem having a wide angle of view. Moreover, the variable magnificationoptical system ZL includes the intermediate group Gn having a negativerefractive power and the vibration-reduction lens group VR (having anegative refractive power) disposed at an image-side of the intermediategroup, and the vibration-reduction lens group VR is moved so as to havea component in the direction orthogonal to the optical axis to performimage blur correction. Therefore, it is possible to suppress theoccurrence of eccentric coma aberration (decentering coma aberration)and one-sided blur during image blur correction and to obtainsatisfactory imaging performance.

The variable magnification optical system ZL satisfies ConditionalExpression (1) below.

1.500<β(Gn)t<100.000   (1)

where

β(Gn)t: an imaging magnification of the intermediate group Gn in thetelephoto end state

Conditional Expression (1) is a conditional expression for restoringincident light converged by the first lens group G1 and the second lensgroup G2 to light (approximately afocal light) substantially parallel tothe optical axis using the intermediate group Gn and guiding the lighttoward the vibration-reduction lens group VR to thereby improve avibration-reduction performance. When Conditional Expression (1) issatisfied, it is possible to secure a bright F-value of approximatelyF2.8 to F3.5 and to correct aberrations including spherical aberrationsatisfactorily.

If the imaging magnification exceeds the upper limit value ofConditional Expression (1), the power of the intermediate group Gn istoo large, the correction of aberrations such as spherical aberration bythe intermediate group Gn is insufficient, and it is difficult to obtaina variable magnification ratio (variable power ratio) of approximately 3or higher

In order to obtain the effect reliably, it is preferable that the upperlimit value of Conditional Expression (1) is set to 50.000. In order toobtain the effect more reliably, it is preferable that the upper limitvalue of Conditional Expression (1) is set to 25.000.

If the imaging magnification is smaller than the lower limit value ofConditional Expression (1), strong convergent light enters thevibration-reduction lens group VR, and it is difficult to suppress theoccurrence of eccentric coma aberration in the telephoto end stateduring image blur correction and the occurrence of one-sided blur in thewide-angle end state. As a result, it is difficult to set the F-value tobe as bright as approximately F2.8 to F3.5. In some cases, theoccurrence of spherical aberration becomes severe, and it may bedifficult to obtain a satisfactory imaging performance.

In order to obtain the effect reliably, it is preferable that the lowerlimit value of Conditional Expression (1) is set to 2.000. In order toobtain the effect more reliably, it is preferable that the lower limitvalue of Conditional Expression (1) is set to 2.500.

Preferably, the variable magnification optical system ZL satisfiesConditional Expression (2) below.

1.360<−f(Gn˜G(VR))w/fw<5.000   (2)

where

f(Gn˜G(VR))w: a composite focal length from the intermediate group Gn tothe vibration-reduction lens group VR in the wide-angle end state

fw: a focal length of the entire system in the wide-angle end state

Conditional Expression (2) is a conditional expression for obtaining avariable magnification ratio of approximately 3 and a satisfactoryoptical performance by appropriately setting the composite focal lengthin the wide-angle end state, of the intermediate group Gn and thevibration-reduction lens group VR. When Conditional Expression (2) issatisfied, it is possible to secure a bright F-value of approximatelyF2.8 to F3.5 and to correct aberrations including spherical aberrationsatisfactorily.

If the focal length ratio exceeds the upper limit value of ConditionalExpression (2), a composite refractive power of the intermediate groupGn and the vibration-reduction lens group VR becomes too small and it isdifficult to secure a variable magnification ratio of approximately 3 inthe entire system. As a result, it is necessary for the second lensgroup G2 or other groups to perform varying magnification, andconsequently, correction of spherical aberration or coma aberration isinsufficient.

In order to obtain the effect reliably, it is preferable that the upperlimit value of Conditional Expression (2) is set to 4.000. In order toobtain the effect more reliably, it is preferable that the upper limitvalue of Conditional Expression (2) is set to 3.000.

If the focal length ratio is smaller than the lower limit value ofConditional Expression (2), the composite refractive power of theintermediate group Gn and the vibration-reduction lens group VR is toolarge and it is difficult to correct spherical aberration and comaaberration. As a result, it is difficult to obtain a satisfactoryimaging performance while obtaining a bright F-value of approximatelyF2.8 to F3.5.

In order to obtain the effect reliably, it is preferable that the lowerlimit value of Conditional Expression (2) is set to 1.400. In order toobtain the effect more reliably, it is preferable that the lower limitvalue of Conditional Expression (2) is set to 1.450.

Preferably, the variable magnification optical system ZL includes animage-side lens group RP having the strongest positive refractive poweramong the lens groups having a positive refractive power disposed closerto the image side than the vibration-reduction lens group VR, thedistance between the image-side lens group RP and thevibration-reduction lens group VR changes upon varying magnification,and preferably, Conditional Expression (3) below is satisfied.

0.400<f(RP)/f(FP)<2.000   (3)

where

f(RP): a focal length of the image-side lens group RP

f(FP): a composite focal length in the wide-angle end state, of lensesdisposed closer to the image plane side than the first lens group G1 anddisposed closer to the object side than the intermediate group Gn

Conditional Expression (3) is a conditional expression for obtaining avariable magnification ratio of approximately 3 and a satisfactoryoptical performance by appropriately setting the refractive power of theimage-side lens group RP. When Conditional Expression (3) is satisfied,it is possible to secure a bright F-value of approximately F2.8 to F3.5and to correct aberrations including spherical aberrationsatisfactorily.

When the focal length ratio exceeds the upper limit value of ConditionalExpression (3), varying magnification by the image-side lens group RP isinsufficient and it is difficult to secure a variable magnificationratio of approximately 3 in the entire system. As a result, it isnecessary to cause the second lens group G2 or other groups to performvarying magnification, and consequently, correction of sphericalaberration or coma aberration is insufficient.

In order to obtain the effect reliably, it is preferable that the upperlimit value of Conditional Expression (3) is set to 1.800. In order toobtain the effect more reliably, it is preferable that the upper limitvalue of Conditional Expression (3) is set to 1.700.

If the focal length ratio is smaller than the lower limit value ofConditional Expression (3), the refractive power of the image-side lensgroup RP is too large and it is difficult to correct sphericalaberration and coma aberration. As a result, it is difficult to obtain asatisfactory imaging performance while obtaining a bright F-value ofapproximately F2.8 to F3.5.

In order to obtain the effect reliably, it is preferable that the lowerlimit value of Conditional Expression (3) is set to 0.500. In order toobtain the effect more reliably, it is preferable that the lower limitvalue of Conditional Expression (3) is set to 0.600.

In the variable magnification optical system ZL, it is preferable thatthe intermediate group Gn has one or more positive lens components andone or more negative lens components.

The “lens component” refers to a single lens or a cemented lens.

Due to this configuration, it is possible to satisfactorily correct thespherical aberration and the coma aberration using the intermediategroup Gn and to improve a vibration-reduction performance. When theintermediate group Gn includes any one of the lens components,correction of spherical aberration and coma aberration by theintermediate group Gn is insufficient, and it is necessary to cause thevibration-reduction lens group VR to correct these aberrations. As aresult, the occurrence of eccentric coma aberration or one-sided bluroccurring during image blur correction is greater, and it is difficultto maintain a satisfactory imaging performance during image blurcorrection.

In order to obtain the effect reliably, it is more preferable that theintermediate group Gn has at least two negative lens components and oneor more positive lens components.

In the variable magnification optical system ZL, it is preferable thatthe second lens group G2 has at least four lens components.

Due to this configuration, it is possible to satisfactorily correctspherical aberration and coma aberration using the second lens group G2and to improve a vibration-reduction performance. When the second lensgroup G2 has three or fewer lens components, since correction ofspherical aberration and coma aberration by the second lens group G2 isinsufficient, it is necessary to cause the intermediate group Gn tocorrect these aberrations. As a result, the occurrence of eccentric comaaberration or one-sided blur occurring during image blur correction isgreater, and it is difficult to maintain a satisfactory imagingperformance during image blur correction.

In order to obtain the effect reliably, it is preferable that the secondlens group G2 has five or more lens components.

In the variable magnification optical system ZL, it is preferable thatthe second lens group G2 is constituted by, in order from the object, a21st lens group G21 having a positive refractive power and a 22nd lensgroup G22 having a positive refractive power, and preferably, focusingfrom an object at infinity to an object at a close distance is performedby moving the 21st lens group G21 to the image side as a focusing lensgroup.

Due to this configuration, it is possible to decrease the size and theweight of the lens group that moves upon focusing and to decrease thesize of an entire lens system and accelerate the focusing speed duringautofocus.

The variable magnification optical system ZL preferably satisfiesConditional Expression (4) below.

10.00°<ωt<30.00°  (4)

where

ωt: a half-angle of view in the telephoto end state

Conditional Expression (4) is a condition that determines the value of ahalf-angle of view in the telephoto end state. When ConditionalExpression (4) is satisfied, it is possible to obtain a desired angle ofview and to satisfactorily correct coma aberration, distortion, and acurvature of field.

In order to obtain the effect reliably, it is preferable that the upperlimit value of Conditional Expression (4) is set to 27.00°. In order toobtain the effect more reliably, it is preferable that the upper limitvalue of Conditional Expression (4) is set to 24.00°.

In order to obtain the effect reliably, it is preferable that the lowerlimit value of Conditional Expression (4) is set to 11.00°. In order toobtain the effect more reliably, it is preferable that the lower limitvalue of Conditional Expression (4) is set to 12.00°.

The variable magnification optical system ZL preferably satisfiesConditional Expression (5) below.

30.00°<ωw<50.00°  (5)

where

ωw: a half-angle of view in the wide-angle end state

Conditional Expression (5) is a condition that specifies the value of ahalf-angle of view in the wide-angle end state. When ConditionalExpression (5) is satisfied, it is possible to obtain a desired angle ofview and to satisfactorily correct coma aberration, distortion, and acurvature of field.

In order to obtain the effect reliably, it is preferable that the upperlimit value of Conditional Expression (5) is set to 48.00°. In order toobtain the effect more reliably, it is preferable that the upper limitvalue of Conditional Expression (5) is set to 45.00°.

In order to obtain the effect reliably, it is preferable that the lowerlimit value of Conditional Expression (5) is set to 32.00°. In order toobtain the effect more reliably, it is preferable that the lower limitvalue of Conditional Expression (5) is set to 34.00°.

In the variable magnification optical system ZL, the distance betweenthe 21st lens group G21 and the 22nd lens group G22 may be fixed orvariable upon varying magnification.

In the variable magnification optical system ZL, the distance betweenthe intermediate group Gn and the vibration-reduction lens group VR maybe fixed or variable upon varying magnification. When the distance isfixed, it is preferable that the composite refractive power of theintermediate group Gn and the vibration-reduction lens group VR isnegative.

In the variable magnification optical system ZL, it is preferable thatan optical system constituted by lenses disposed closer to the imageside than the vibration-reduction lens group VR has a positiverefractive power.

The variable magnification optical system ZL preferably has at least onelens group having a positive refractive power on a side closer to theimage side than the vibration-reduction lens group VR.

The variable magnification optical system ZL preferably has an aperturestop between the second lens group G2 and the intermediate group Gn.

In this way, it is possible to implement a variable magnificationoptical system ZL which has a bright F-value and a wide angle of viewand in which aberrations are corrected satisfactorily.

Next, a camera (an optical apparatus) having the above-describedvariable magnification optical system ZL will be described withreference to the drawings. FIG. 37 illustrates an example of aconfiguration of a camera having a variable magnification optical systemmounted thereon.

As illustrated in FIG. 37, a camera 1 is an interchangeable lens camera(so-called a mirrorless camera) having the above-described variablemagnification optical system ZL as an image capturing lens 2. In thiscamera 1, light from an object (a subject) which is not illustrated iscollected by the image capturing lens 2 and forms a subject image on animage plane of the imaging unit 3 via an optical low-pass filter (OLPF)which is not illustrated. The subject image is photoelectricallyconverted by a photoelectric conversion element provided in the imagingunit 3, whereby the image of the object is generated. This image isdisplayed on an electronic viewfinder (EVF) 4 provided in the camera 1.In this way, a photographer can view the subject via the EVF 4.Moreover, when a release button (not illustrated) is pressed by thephotographer, the image of the subject generated by the imaging unit 3is stored in a memory (not illustrated). In this way, the photographercan capture the image of the subject using the camera 1.

As can be understood from respective examples to be described later, thevariable magnification optical system ZL mounted on the camera 1 as theimage capturing lens 2 has a bright F-value and a wide angle of view andhas a satisfactory optical performance such that aberrations arecorrected satisfactorily due to its characteristic lens configuration.Therefore, according to the camera 1, it is possible to implement anoptical apparatus which has a bright F-value and a wide angle of viewand has a satisfactory optical performance such that aberrations arecorrected satisfactorily.

Although a mirrorless camera has been described as an example of thecamera 1, the camera is not limited to this. For example, the sameeffect as the camera 1 can be obtained even when the above-describedvariable magnification optical system ZL is mounted on a single-lensreflex camera which has a quick return mirror on a camera body and viewsa subject using a finder optical system.

Next, an example of a method for manufacturing the above-describedvariable magnification optical system ZL will be described. FIG. 38illustrate an example of a method for manufacturing the variablemagnification optical system ZL.

First, respective lenses are arranged in a lens barrel so as to includea first lens group G1 having a negative refractive power and a secondlens group G2 having a positive refractive power (step ST10). Respectivelenses are arranged so as to have an intermediate group Gn disposedcloser to an image side than the second lens group G2 (step ST20).Respective lenses are arranged so as to have a vibration-reduction lensgroup VR disposed closer to the image side than the intermediate groupGn and configured to be movable so as to have a component in thedirection orthogonal to the optical axis (step ST30). Respective lensesare arranged so that varying magnification is performed by changing atleast the distance between the first lens group G1 and the second lensgroup G2 and the distance between the second lens group G2 and theintermediate group Gn (step ST40). The respective lenses are arranged soas to satisfy Conditional Expression (1) below (step ST50).

1.500<β(Gn)t<100.000   (1)

where

β(Gn)t: an imaging magnification of the intermediate group Gn in thetelephoto end state

According to an example of a lens arrangement, as illustrated in FIG. 1,a negative meniscus lens L11 having a concave surface oriented toward animage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side are arranged, inorder from the object, to form the first lens group G1. A biconvex lensL21, a positive meniscus lens L22 having a convex surface orientedtoward the object side, a cemented lens including a biconvex lens L23and a biconcave lens L24, and a biconvex lens L25 are arranged, in orderfrom the object, to form the 21st lens group G21. A biconvex lens L26 isarranged to form the 22nd lens group G22. A biconcave lens L31, anegative meniscus lens L32 having a concave surface oriented toward theobject side, and a biconvex lens L33 are arranged, in order from theobject, to form the 31st lens group G31. A biconcave lens L34 and apositive meniscus lens L35 having a convex surface oriented toward theobject side are arranged, in order from the object, to form the 32ndlens group G32. A biconvex lens L41, a cemented lens including anegative meniscus lens L42 having a concave surface oriented toward theimage side and a biconvex lens L43, and a cemented lens including abiconvex lens L44, a biconcave lens L45, and a positive meniscus lensL46 having a convex surface oriented toward the object side are, inorder from the object, to form the fourth lens group G4. The respectivelens groups prepared in this manner are arranged in the above-describedorder to manufacture the variable magnification optical system ZL.

According to the above-described manufacturing method, it is possible tomanufacture the variable magnification optical system ZL which has abright F-value and a wide angle of view and in which aberrations arecorrected satisfactorily.

EXAMPLES

Hereinafter, respective examples will be described with reference to thedrawings.

FIGS. 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, and 34 arecross-sectional views illustrating the configuration and the refractivepower allocation of variable magnification optical systems ZL (ZL1 toZL12) according to respective examples. In the lower part of thecross-sectional views of the variable magnification optical systems ZL1to ZL12, the moving directions along the optical axis of each lens groupupon varying magnification from the wide-angle end state (W) to thetelephoto end state (T) via the intermediate focal length state (M) areindicated by arrows. In the upper part of the cross-sectional views ofthe variable magnification optical systems ZL1 to ZL13, the movingdirection of the focusing lens group upon focusing from an object atinfinity to an object at a close distance is indicated by an arrow andthe state of the vibration-reduction lens group VR when correcting imageblur is also illustrated.

Respective reference signs in FIG. 1 associated with Example 1 are usedindependently in respective examples in order to avoid complication ofdescription due to an increased number of reference sign characters.Therefore, even when components in diagrams associated with otherexamples are denoted by the same reference signs as used in FIG. 1,these components do not necessarily have the same configuration as thoseof other examples.

Tables 1 to 12 illustrated below are tables of respective specificationsof Examples 1 to 12.

In the respective examples, the d-line (wavelength: 587.562 nm) and theg-line (wavelength: 435.835 nm) are selected as an aberrationcharacteristics calculation target.

In [Lens Specification] in tables, a surface number indicates a sequencenumber of an optical surface from an object side along a travelingdirection of light, R indicates a radius of curvature of each opticalsurface, D indicates a surface distance which is the distance on theoptical axis from each optical surface to the next optical surface (oran image plane), nd indicates a refractive index for the d-line, of amaterial of an optical member, νd indicates the Abbe number for thed-line, of a material of an optical member, and Aperture stop indicatesan aperture stop S. When the radius of curvature is “0.00000,” thisindicates a flat surface for a lens surface and indicates an aperture ora diaphragm surface for an aperture stop. When the optical surface is anaspherical surface, a mark “*” is assigned to the surface number and aparaxial radius of curvature is shown in the radius of curvature columnR.

In [Aspheric Data] in tables, the shape of an aspherical surface shownin [Lens Specification] is expressed by Equation (a) below. X(y)indicates the distance along the optical axis direction from atangential plane at the vertex of an aspherical surface to a position onthe aspherical surface at a height y, R indicates a radius of curvature(a paraxial radius of curvature) of a reference spherical surface, κindicates a conic constant, and Ai indicates an aspheric coefficient atdegree i. “E-n” indicates “×10^(−n)”. For example, 1.234E−05=1.234×10⁻⁵.An aspheric coefficient A2 at degree 2 is 0 and is not illustrated.

X(y)=(y ² /R)/{1+(1−κ×y ² /R ²)^(1/2) }+A4×y ⁴ +A6×y ⁶ +A8×y ⁸ +A10×y ¹⁰+A12×y ¹²(a)

In [Various Data] in tables, f indicates a focal length of an entirelens system, FNo indicates the F-number, ω indicates a half-angle ofview (unit: °), Y indicates the maximum image height, TL indicates thedistance from the frontmost lens surface to the last lens surface on theoptical axis upon focusing on infinity, BF indicates the distance fromthe last lens surface to the image plane I on the optical axis uponfocusing on infinity, and BF (air-conversion length) indicates thedistance (an air-conversion length) from the last lens surface to theimage plane I on the optical axis upon focusing on infinity.

In [Variable Distance Data] in tables, D0 indicates an axial airdistance between an object plane and a lens surface closest to anobject, of the first lens group G1, Di indicates a surface distance(i=1, 2, 3, . . . ) between an i-th surface and an (i+1)th surface, andf indicates the focal length of an entire lens system.

In [Lens Group Data] in tables, a starting surface and a focal length ofeach lens group are illustrated.

In [Focusing Data] in tables, a lens moving distance and an imagingdistance upon focusing are illustrated.

In [Conditional Expression Correspondence Values] in tables, valuescorresponding to Conditional Expressions (1) to (5) are illustrated.

Hereinafter, “mm” is generally used as the unit of the focal length f,the radius of curvature R, the surface distance D, and other lengths andthe like described in all specification values unless particularlystated otherwise. However, the unit is not limited to this since anequivalent optical performance is obtained even when the optical systemis proportionally expanded or reduced. Moreover, the unit is not limitedto “mm” and other appropriate units may be used.

The above description of tables is common to all examples, anddescription thereof will not be provided below.

Example 1

Example 1 will be described with reference to FIGS. 1 to 3 and Table 1.As illustrated in FIG. 1, a variable magnification optical system ZL(ZL1) according to Example 1 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a negative refractive power, and a fourth lens group G4 having apositive refractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, abiconvex lens L21, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25. The 22ndlens group G22 is constituted by a biconvex lens L26.

The third lens group G3 is constituted by, in order from the object, a31st lens group G31 (an intermediate group) of which the position in thedirection orthogonal to the optical axis is immovable and which hasnegative refractive power and a 32nd lens group G32 (avibration-reduction lens group) having a negative refractive power.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31, a negative meniscus lens L32 having a concavesurface oriented toward the object side, and a biconvex lens L33. The32nd lens group G32 is constituted by, in order from the object, abiconcave lens L34 and a positive meniscus lens L35 having a convexsurface oriented toward the object side.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a cemented lens including a negative meniscus lensL42 having a concave surface oriented toward the image side and abiconvex lens L43, and a cemented lens including a biconvex lens L44, abiconcave lens L45, and a positive meniscus lens L46 having a convexsurface oriented toward the object side. The biconvex lens L41 has anaspherical object-side surface. The positive meniscus lens L46 has anaspherical image-side surface.

A first flare-cut diaphragm FC1 and an aperture stop S arranged in thatorder from the object are disposed between the second lens group G2 andthe third lens group G3. A second flare-cut diaphragm FC2 is disposedbetween the fourth lens group G4 and the image plane I.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the image side and then moving the same toward theobject side, and moving the fourth lens group G4 toward the object sidesuch that the distances between the respective lens groups are changed.The first flare-cut diaphragm FC1, the aperture stop S, and the secondflare-cut diaphragm FC2 are immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is κ, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 1, in the wide-angle end state, since the vibration reductioncoefficient is −0.45 and the focal length is 24.80 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.29 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.51 and the focallength is 50.01 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.51 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.58and the focal length is 67.85 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.61 mm.

Table 1 illustrates the values of respective specifications ofExample 1. Surface numbers 1 to 40 in Table 1 correspond to opticalsurfaces of m1 to m40 illustrated in FIG. 1.

TABLE 1 [Lens Specification] Surface number R D n (d) νd 1 121.856382.900 1.74389 49.5 *2 29.63670 15.360  1.00000 *3 −197.50816 0.2001.56093 36.6 4 −169.39125 2.100 1.80400 46.6 5 60.51496 0.150 1.00000 652.85097 5.600 2.00100 29.1 7 146.47986 D7  1.00000 8 148.41161 3.0001.59349 67.0 9 −517.10678 0.100 1.00000 10 49.87002 3.500 1.59349 67.011 157.35190 4.762 1.00000 12 87.49334 4.800 1.59349 67.0 13 −132.224001.500 1.90366 31.3 14 45.76622 1.640 1.00000 15 78.93526 4.450 1.7725049.6 16 −176.75459 D16 1.00000 17 57.14809 5.300 1.81600 46.6 18−583.40702 D18 1.00000 19 0.00000 1.200 1.00000 20 (Aperture stop) D201.00000 21 −141.85186 1.200 1.80400 46.6 22 33.20059 4.360 1.00000 23−33.72704 1.200 1.60300 65.4 24 −60.09530 0.100 1.00000 25 65.488683.150 1.84666 23.8 26 −127.25009 D26 1.00000 27 −119.24441 1.100 1.5934967.0 28 67.70394 1.150 1.00000 29 62.36800 2.100 1.80518 25.5 30107.42000 D30 1.00000 *31 119.87584 4.700 1.55332 71.7 32 −115.001290.100 1.00000 33 71.95116 1.400 1.83481 42.7 34 38.48800 6.800 1.5931967.9 35 −237.01429 0.280 1.00000 36 43.00799 9.500 1.49782 82.6 37−42.99900 1.400 1.80518 25.5 38 98.94100 4.600 1.69350 53.3 *39462.40647 D39 1.00000 40 0.00000 D40 1.00000 [Aspheric Data] 2nd surfaceκ = 0.00000e+00 A4 = 2.21510e−06 A6 = 2.57690e−09 A8 = −6.01500e−12 A10= 1.09200e−14 A12 = −7.29000e−18 3rd surface κ = 1.00000e+00 A4 =−3.83430e−07 A6 = 7.93340e−10 A8 = −3.53630e−12 A10 = 5.08120e−15 A12 =−3.43370e−18 31st surface κ = 1.00000e+00 A4 = 4.80890e−06 A6 =5.06980e−10 A8 = −2.73140e−12 A10 = −7.78150e−16 A12 = 0.00000e+00 39thsurface κ = 1.00000e+00 A4 = 7.56540e−06 A6 = −9.88600e−10 A8 =5.61740e−12 A10 = −8.07750e−15 A12 = 0.00000e+00 [Various Data] W M T f24.80 50.01 67.85 FNo 2.92 2.92 2.92 ω 42.5 22.7 17.2 Y 21.60 21.6021.60 TL 220.251 198.419 200.827 BF 41.035 48.522 55.686 BF(air-conversion length) 41.035 48.522 55.686 [Variable Distance Data]Focusing on infinity W M T D0 ∞ ∞ ∞ Magnification — — — f 24.80 50.0167.85 D7 48.945 10.930 1.902 D16 7.735 7.735 7.735 D18 1.802 17.93129.439 D20 2.088 4.668 3.620 D26 1.250 1.250 1.250 D30 17.692 7.6801.492 D39 2.530 10.000 17.180 D40 38.505 38.522 38.506 [Lens Group Data]Lens group Starting surface Focal length 1st lens group 1 −38.47 2ndlens group 8 42.49 21st lens group 8 78.58 22nd lens group 17 64.02 3rdlens group 21 −39.26 31st lens group 21 −65.76 32nd lens group 27−121.07 4th lens group 31 48.95 [Focusing Data] W M T Lens moving 6.7356.735 6.735 distance Imaging distance 0.4183 0.3810 0.3966 (m)[Conditional Expression Correspondence Values] Conditional Expression(1) β(Gn)t = 12.080 Conditional Expression (2) −f(Gn~G(VR))w/fw = 1.583Conditional Expression (3) f(RP)/f(FP) = 1.152 Conditional Expression(4) ωt = 17.2 Conditional Expression (5) ωw = 42.5

It can be understood from Table 1 that the variable magnificationoptical system ZL1 according to Example 1 satisfies ConditionalExpressions (1) to (5).

FIG. 2 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration(lateral chromatic aberration), and lateral aberration) upon focusing oninfinity, of the variable magnification optical system ZL1 according toExample 1, in which part (a) illustrates the wide-angle end state, part(b) illustrates the intermediate focal length state, and part (c)illustrates the telephoto end state. FIG. 3 shows graphs illustratinglateral aberration of the variable magnification optical system ZL1according to Example 1 when image blur correction is performed uponfocusing on infinity, in which part (a) illustrates the wide-angle endstate, part (b) illustrates the intermediate focal length state, andpart (c) illustrates the telephoto end state. In this example, theoptical performance during vibration reduction is illustrated as alateral aberration graph corresponding to an image height of ±15.10about the image height y=0.0 as illustrated in FIG. 3.

In the graphs illustrating respective aberrations, FNO indicates theF-number and Y indicates an image height. d indicates aberration at thed-line and g indicates aberration at the g-line. Moreover, aberrationswithout these characters indicate aberrations at the d-line. In thegraphs illustrating the spherical aberration upon focusing on infinity,the F-number values corresponding to the maximum aperture areillustrated. In the graphs illustrating the astigmatism, a solid lineindicates the sagittal image plane and a broken line indicates themeridional image plane. The same reference symbols as in this exampleare used in the aberration graphs of respective examples to be describedlater.

As is obvious from respective aberration graphs, it can be understoodthat the variable magnification optical system ZL1 according to Example1 has a satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it can be understood that thevariable magnification optical system ZL1 has an excellent imagingperformance upon image blur correction.

Example 2

Example 2 will be described with reference to FIGS. 4 to 6 and Table 2.As illustrated in FIG. 4, a variable magnification optical system ZL(ZL2) according to Example 2 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a negative refractive power, and a fourth lens group G4 having apositive refractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, abiconvex lens L21, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25. The 22ndlens group G22 is constituted by a biconvex lens L26.

The third lens group G3 is constituted by, in order from the object, a31st lens group G31 (an intermediate group) of which the position in thedirection orthogonal to the optical axis is immovable and which hasnegative refractive power and a 32nd lens group G32 (avibration-reduction lens group) having a negative refractive power.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31, a negative meniscus lens L32 having a concavesurface oriented toward the object side, and a biconvex lens L33. The32nd lens group G32 is constituted by, in order from the object, abiconcave lens L34 and a positive meniscus lens L35 having a convexsurface oriented toward the object side. The biconcave lens L34 has anaspherical object-side surface.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a cemented lens including a negative meniscus lensL42 having a concave surface oriented toward the image side and abiconvex lens L43, and a cemented lens including a biconvex lens L44, abiconcave lens L45, and a positive meniscus lens L46 having a convexsurface oriented toward the object side. The biconvex lens L41 has anaspherical object-side surface. The positive meniscus lens L46 has anaspherical image-side surface.

An aperture stop S is disposed between the second lens group G2 and thethird lens group G3. A flare-cut diaphragm FC is disposed between thefourth lens group G4 and the image plane I.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the image side and then moving the same toward theobject side, and moving the fourth lens group G4 toward the object sidesuch that the distances between the respective lens groups are changed.The aperture stop S and the flare-cut diaphragm FC are immovable uponvarying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 2, in the wide-angle end state, since the vibration reductioncoefficient is −0.44 and the focal length is 24.80 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.30 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.50 and the focallength is 47.76 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.50 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.58and the focal length is 67.85 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.62 mm.

Table 2 illustrates the values of respective specifications of Example2. Surface numbers 1 to 39 in Table 2 correspond to optical surfaces ofm1 to m39 illustrated in FIG. 4.

TABLE 2 [Lens Specification] Surface number R D n (d) νd 1 123.868342.900 1.74389 49.5 *2 29.53373 15.066  1.00000 *3 −163.51331 0.3001.56093 36.6 4 −139.86223 2.100 1.80400 46.6 5 65.45825 0.150 1.00000 656.53091 5.625 2.00100 29.1 7 182.99126 D7  1.00000 8 143.07855 3.2001.59349 67.0 9 −394.38588 0.200 1.00000 10 55.12400 3.500 1.59349 67.011 197.46867 3.900 1.00000 12 77.75166 4.842 1.59349 67.0 13 −158.022251.500 1.90366 31.3 14 46.02834 1.844 1.00000 15 83.85157 3.848 1.7725049.6 16 −277.24360 D16 1.00000 17 59.19194 5.400 1.80400 46.6 18−354.91781 D18 1.00000 19 (Aperture stop) D19 1.00000 20 −140.000001.178 1.77250 49.6 21 33.57372 4.337 1.00000 22 −36.69329 1.200 1.5934967.0 23 −63.63544 0.100 1.00000 24 61.90037 3.102 1.84666 23.8 25−187.23382 D25 1.00000 *26 −120.15188 1.100 1.61000 65.0 27 78.566670.966 1.00000 28 66.22584 1.921 1.80518 25.5 29 108.00000 D29 1.00000*30 96.36461 5.000 1.55332 71.7 31 −132.37171 0.200 1.00000 32 103.355321.300 1.80518 25.5 33 49.66548 6.742 1.59319 67.9 34 −101.36549 0.1881.00000 35 55.76221 9.450 1.49782 82.6 36 −36.89155 1.400 1.75000 31.437 97.48202 4.003 1.69350 53.2 *38 442.81061 D38 1.00000 39 0.00000 D391.00000 [Aspheric Data] Surface κ A4 A6 A8 A10 2 1.48700e−01 1.33488e−061.45328e−09 −6.97898e−13 5.22062e−16 3 4.31460e+00 −4.66997e−074.80176e−10 −1.05569e−12 3.62706e−16 26 −2.40000e+01 −1.76198e−061.30497e−09 0.00000e+00 0.00000e+00 30 3.97310e+00 3.04836e−06−6.62447e−10 0.00000e+00 0.00000e+00 38 3.71000e+02 4.89412e−061.67774e−10 0.00000e+00 0.00000e+00 [Various Data] W M T f 24.80 47.7667.85 FNo 2.92 2.92 2.92 ω 42.5 23.7 17.2 Y 21.60 21.60 21.60 TL 219.362198.056 201.131 BF 41.459 48.894 57.632 BF (air-conversion length)41.459 48.894 57.632 [Variable Distance Data] Focusing on infinity W M TD0 ∞ ∞ ∞ Magnification — — — f 24.80 47.76 67.85 D7 48.978 12.578 1.835D16 7.750 7.750 7.750 D18 3.000 18.144 31.911 D19 2.000 4.200 2.500 D251.440 1.440 1.440 D29 18.172 8.487 1.500 D38 1.139 8.574 17.251 D3940.319 40.320 40.381 [Lens Group Data] Lens group Starting surface Focallength 1st lens group 1 −38.77 2nd lens group 8 42.97 21st lens group 881.61 22nd lens group 17 63.47 3rd lens group 20 −40.68 31st lens group20 −68.40 32nd lens group 26 −123.54 4th lens group 30 49.36 [FocusingData] W M T Lens moving 6.75 6.75 6.75 distance Imaging distance 0.41240.3853 0.4059 (m) [Conditional Expression Correspondence Values]Conditional Expression (1) β(Gn)t = 13.824 Conditional Expression (2)−f(Gn~G(VR))w/fw = 1.640 Conditional Expression (3) f(RP)/f(FP) = 1.149Conditional Expression (4) ωt = 17.2 Conditional Expression (5) ωw =42.5

It is understood from Table 2 that the variable magnification opticalsystem ZL2 according to Example 2 satisfies Conditional Expressions (1)to (5).

FIG. 5 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL2 according to Example 2, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 6 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL2 according to Example 2 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 6.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL2 according to Example 2 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL2 has an excellent imaging performanceupon image blur correction.

Example 3

Example 3 will be described with reference to FIGS. 7 to 9 and Table 3.As illustrated in FIG. 7, a variable magnification optical system ZL(ZL3) according to Example 3 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a negative refractive power, a fourth lens group G4 having apositive refractive power, and a fifth lens group G5 having a positiverefractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, abiconvex lens L21, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25. The 22ndlens group G22 is constituted by a biconvex lens L26.

The third lens group G3 is constituted by, in order from the object, a31st lens group G31 (an intermediate group) of which the position in thedirection orthogonal to the optical axis is immovable and which hasnegative refractive power and a 32nd lens group G32 (avibration-reduction lens group) having a negative refractive power.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31, a negative meniscus lens L32 having a concavesurface oriented toward the object side, and a biconvex lens L33. The32nd lens group G32 is constituted by, in order from the object, abiconcave lens L34 and a positive meniscus lens L35 having a convexsurface oriented toward the object side. The biconcave lens L34 has anaspherical object-side surface.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a cemented lens including a negative meniscus lensL42 having a concave surface oriented toward the image side and abiconvex lens L43, and a cemented lens including a biconvex lens L44 anda biconcave lens L45. The biconvex lens L41 has an asphericalobject-side surface. The biconcave lens L45 has an aspherical image-sidesurface.

The fifth lens group G5 is constituted by a cemented lens including, inorder from an object, a positive meniscus lens L51 having a convexsurface oriented toward the object side and a negative meniscus lens L52having a concave surface oriented toward the image side.

An aperture stop S is disposed between the second lens group G2 and thethird lens group G3.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the image side and then moving the same toward theobject side, and moving the fourth lens group G4 toward the object sidesuch that the distances between the respective lens groups are changed.The fifth lens group G5 and the aperture stop S are immovable uponvarying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 3, in the wide-angle end state, since the vibration reductioncoefficient is −0.45 and the focal length is 24.82 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.29 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.50 and the focallength is 47.49 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.49 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.58and the focal length is 67.84 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.62 mm.

Table 3 illustrates the values of respective specifications of Example3. Surface numbers 1 to 40 in Table 3 correspond to optical surfaces ofm1 to m40 illustrated in FIG. 7.

TABLE 3 [Lens Specification] Surface number R D n(d) νd 1 134.614342.900 1.74389 49.5 *2 30.98121 14.105  1.00000 *3 −271.55507 0.3001.56093 36.6 4 −224.01871 2.100 1.80400 46.6 5 65.07720 0.200 1.00000 653.84066 5.401 2.00100 29.1 7 113.70514 D7  1.00000 8 259.91458 3.0001.59349 67.0 9 −443.80327 0.243 1.00000 10 71.84029 3.500 1.69680 55.511 238.64880 4.057 1.00000 12 66.72188 5.288 1.59349 67.0 13 −145.977381.500 1.90366 31.3 14 49.38387 1.625 1.00000 15 83.91292 4.117 1.7725049.6 16 −207.54373 D16 1.00000 17 59.58569 5.400 1.80400 46.6 18−338.02309 D18 1.00000 19 (Aperture stop) D19 1.00000 20 −140.000001.178 1.77250 49.6 21 34.70000 4.110 1.00000 22 −37.39824 1.200 1.5934967.0 23 −64.12090 0.100 1.00000 24 62.46432 2.941 1.90200 25.3 25−277.86426 D25 1.00000 *26 −157.84803 1.100 1.77250 49.6 27 61.660831.232 1.00000 28 63.26230 2.386 1.84666 23.8 29 198.11149 D29 1.00000*30 74.15506 5.000 1.55332 71.7 31 −190.85228 0.100 1.00000 32 414.998631.300 1.84666 23.8 33 79.29491 6.640 1.59319 67.9 34 −59.47223 0.1881.00000 35 77.14715 8.284 1.49700 81.6 36 −39.12349 1.400 1.70600 30.9*37 467.32553 D37 1.00000 38 74.86867 2.769 1.49700 81.6 39 177.017931.400 1.79504 28.7 40 100.00000 D40 1.00000 [Aspheric Data] Surface κ A4A6 A8 A10 2 −8.40000e−03 1.76676e−06 1.42633e−09 −6.16355e−133.36393e−16 3 5.89560e+00 −4.29758e−07 9.43230e−10 −1.79782e−128.72339e−16 26 −2.40000e+01 −5.18855e−07 4.69601e−10 0.00000e+000.00000e+00 30 7.93900e−01 2.20229e−06 −7.31449e−10 0.00000e+000.00000e+00 37 4.51000e+02 4.05983e−06 9.42292e−10 0.00000e+000.00000e+00 [Various Data] W M T f 24.82 47.49 67.84 FNo 2.91 2.91 2.92ω 42.3 23.8 17.2 Y 21.60 21.60 21.60 TL 220.442 198.936 201.965 BF42.289 42.290 42.353 BF (air-conversion length) 42.289 42.290 42.353[Variable Distance Data] Focusing on infinity W M T D0 ∞ ∞ ∞Magnification — — — f 24.82 47.49 67.84 D7 49.018 12.832 1.835 D16 7.7507.750 7.750 D18 3.000 17.679 31.753 D19 2.000 3.989 2.000 D25 1.4121.412 1.412 D29 18.411 8.690 1.500 D37 1.500 9.233 18.301 D40 42.28942.290 42.353 [Lens Group Data] Lens group Starting surface Focal length1st lens group 1 −38.85 2nd lens group 8 42.32 21st lens group 8 82.2122nd lens group 17 63.39 3rd lens group 20 −41.39 31st lens group 20−69.44 32nd lens group 26 −122.74 4th lens group 30 52.58 5th lens group38 2000.09 [Focusing Data] W M T Lens moving distance 6.75 6.75 6.75Imaging distance (m) 0.4144 0.3857 0.4059 [Conditional ExpressionCorrespondence Values] Conditional Expression (1) β(Gn)t = 9.843Conditional Expression (2) −f(Gn~G(VR))w/fw = 1.668 ConditionalExpression (3) f(RP)/f(FP) = 1.242 Conditional Expression (4) ωt = 17.2Conditional Expression (5) ωw = 42.3

It is understood from Table 3 that the variable magnification opticalsystem ZL3 according to Example 3 satisfies Conditional Expressions (1)to (5).

FIG. 8 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL3 according to Example 3, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 9 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL3 according to Example 3 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 9.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL3 according to Example 3 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL3 has an excellent imaging performanceupon image blur correction.

Example 4

Example 4 will be described with reference to FIGS. 10 to 12 and Table4. As illustrated in FIG. 10, a variable magnification optical system ZL(ZL4) according to Example 4 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a positive refractive power, a fourth lens group G4 having anegative refractive power, a fifth lens group G5 having a negativerefractive power, a sixth lens group G6 having a positive refractivepower, and a seventh lens group G7 having a negative refractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 (a focusing lens group) is constituted by abiconvex lens L21, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25.

The third lens group G3 is constituted by a biconvex lens L31.

The fourth lens group G4 (an intermediate group) is constituted by, inorder from the object, a biconcave lens L41, a negative meniscus lensL42 having a concave surface oriented toward the object side, and abiconvex lens L43, of which the positions in the direction orthogonal tothe optical axis are immovable.

The fifth lens group G5 (a vibration-reduction lens group) isconstituted by, in order from the object, a biconcave lens L51 and apositive meniscus lens L52 having a convex surface oriented toward theobject side. The biconcave lens L51 has an aspherical object-sidesurface.

The sixth lens group G6 is constituted by, in order from the object, abiconvex lens L61, a cemented lens including a negative meniscus lensL62 having a concave surface oriented toward the image side and abiconvex lens L63, and a cemented lens including a biconvex lens L64 anda biconcave lens L65. The biconvex lens L61 has an asphericalobject-side surface. The biconcave lens L65 has an aspherical image-sidesurface.

The seventh lens group G7 is constituted by a cemented lens including,in order from an object, a positive meniscus lens L71 having a convexsurface oriented toward the object side and a negative meniscus lens L72having a concave surface oriented toward the image side.

An aperture stop S is disposed between the third lens group G3 and thefourth lens group G4.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the object side, moving the fourth lens group G4toward the image side and then moving the same toward the object side,moving the fifth lens group G5 toward the image side and then moving thesame toward the object side, and moving the sixth lens group G6 towardthe object side such that the distances between the respective lensgroups are changed. The seventh lens group G7 and the aperture stop Sare immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the second lens group G2 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the fifth lens group G5 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 4, in the wide-angle end state, since the vibration reductioncoefficient is −0.46 and the focal length is 25.49 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.29 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.53 and the focallength is 48.81 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.49 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.61and the focal length is 69.45 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.59 mm.

Table 4 illustrates the values of respective specifications of Example4. Surface numbers 1 to 40 in Table 4 correspond to optical surfaces ofm1 to m40 illustrated in FIG. 10.

TABLE 4 [Lens Specification] Surface number R D n (d) νd 1 134.614342.900 1.74389 49.5 *2 30.98121 14.105  1.00000 *3 −271.55507 0.3001.56093 36.6 4 −224.01871 2.100 1.80400 46.6 5 65.07720 0.200 1.00000 653.84066 5.401 2.00100 29.1 7 113.70514 D7  1.00000 8 259.91458 3.0001.59349 67.0 9 −443.80327 0.243 1.00000 10 71.84029 3.500 1.69680 55.511 238.64880 4.057 1.00000 12 66.72188 5.288 1.59349 67.0 13 −145.977381.500 1.90366 31.3 14 49.38387 1.625 1.00000 15 83.91292 4.117 1.7725049.6 16 −207.54373 D16 1.00000 17 59.58569 5.400 1.80400 46.6 18−338.02309 D18 1.00000 19 (Aperture stop) D19 1.00000 20 −140.000001.178 1.77250 49.6 21 34.70000 4.110 1.00000 22 −37.39824 1.200 1.5934967.0 23 −64.12090 0.100 1.00000 24 62.46432 2.941 1.90200 25.3 25−277.86426 D25 1.00000 *26 −157.84803 1.100 1.77250 49.6 27 61.660831.232 1.00000 28 63.26230 2.386 1.84666 23.8 29 198.11149 D29 1.00000*30 74.15506 5.000 1.55332 71.7 31 −190.85228 0.100 1.00000 32 414.998631.300 1.84666 23.8 33 79.29491 6.640 1.59319 67.9 34 −59.47223 0.1881.00000 35 77.14715 8.284 1.49700 81.6 36 −39.50000 1.400 1.70600 30.9*37 467.32553 D37 1.00000 38 74.86867 2.769 1.48749 70.3 39 300.000001.400 1.79504 28.7 40 100.00000 D40 1.00000 [Aspheric Data] Surface κ A4A6 A8 A10 2 −8.40000e−03 1.76676e−06 1.42633e−09 −6.16355e−133.36393e−16 3 5.89560e+00 −4.29758e−07 9.43230e−10 −1.79782e−128.72339e−16 26 −2.40000e+01 −5.18855e−07 4.69601e−10 0.00000e+000.00000e+00 30 7.93900e−01 2.20229e−06 −7.31449e−10 0.00000e+000.00000e+00 37 4.51000e+02 4.05983e−06 9.42292e−10 0.00000e+000.00000e+00 [Various Data] W M T f 25.49 48.81 69.45 FNo 2.92 2.92 2.92ω 41.6 23.3 16.8 Y 21.60 21.60 21.60 TL 222.079 204.772 203.978 BF44.388 45.157 44.803 BF (air-conversion length) 44.388 45.157 44.803[Variable Distance Data] Focusing on infinity W M T D0 ∞ ∞ ∞Magnification — — — f 25.49 48.81 69.45 D7 49.018 12.832 1.900 D16 7.75012.000 8.300 D18 2.500 16.500 30.700 D19 2.000 3.989 2.000 D25 1.4123.000 1.412 D29 18.450 7.000 1.500 D37 1.500 9.233 18.301 D40 44.38845.157 44.803 [Lens Group Data] Lens group Starting surface Focal length1st lens group 1 −38.85 2nd lens group 8 82.21 3rd lens group 17 63.394th lens group 20 −69.44 5th lens group 26 −122.74 6th lens group 3052.47 7th lens group 38 −3528.86 [Focusing Data] W M T Lens moving 6.7511.00 7.30 distance Imaging distance 0.4160 0.3019 0.3889 (m)[Conditional Expression Correspondence Values] Conditional Expression(1) β(Gn)t = 11.069 Conditional Expression (2) −f(Gn~G(VR))w/fw = 1.624Conditional Expression (3) f(RP)/f(FP) = 1.240 Conditional Expression(4) ωt = 16.8 Conditional Expression (5) ωw = 41.6

It is understood from Table 4 that the variable magnification opticalsystem ZL4 according to Example 4 satisfies Conditional Expressions (1)to (5).

FIG. 11 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL4 according to Example 4, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 12 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL4 according to Example 4 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 12.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL4 according to Example 4 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL4 has an excellent imaging performanceupon image blur correction.

Example 5

Example 5 will be described with reference to FIGS. 13 to 15 and Table5. As illustrated in FIG. 13, a variable magnification optical system ZL(ZL5) according to Example 5 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a negative refractive power, a fourth lens group G4 having apositive refractive power, and a fifth lens group G5 having a positiverefractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, abiconvex lens L21, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25. The 22ndlens group G22 is constituted by a biconvex lens L26.

The third lens group G3 is constituted by, in order from the object, anaperture stop S, a 31st lens group G31 (an intermediate group) of whichthe position in the direction orthogonal to the optical axis isimmovable and which has negative refractive power and a 32nd lens groupG32 (a vibration-reduction lens group) having a negative refractivepower.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31, a negative meniscus lens L32 having a concavesurface oriented toward the object side, and a biconvex lens L33. The32nd lens group G32 is constituted by, in order from the object, abiconcave lens L34 and a positive meniscus lens L35 having a convexsurface oriented toward the object side. The biconcave lens L34 has anaspherical object-side surface.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a cemented lens including a negative meniscus lensL42 having a concave surface oriented toward the image side and abiconvex lens L43, and a cemented lens including a biconvex lens L44 anda biconcave lens L45. The biconvex lens L41 has an asphericalobject-side surface. The biconcave lens L45 has an aspherical image-sidesurface.

The fifth lens group G5 is constituted by a cemented lens including abiconvex lens L51 and a biconcave lens L52 arranged in that order fromthe object.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, and moving thefourth lens group G4 toward the object side such that the distancesbetween the respective lens groups are changed. The third lens group G3and the fifth lens group G5 are immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 5, in the wide-angle end state, since the vibration reductioncoefficient is −0.46 and the focal length is 24.77 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.28 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.52 and the focallength is 47.50 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.48 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.58and the focal length is 67.85 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.62 mm.

Table 5 illustrates the values of respective specifications of Example5. Surface numbers 1 to 40 in Table 5 correspond to optical surfaces ofm1 to m40 illustrated in FIG. 13.

TABLE 5 [Lens Specification] Surface number R D n(d) νd 1 144.948172.900 1.74389 49.5 *2 29.83529 14.301 1.00000 *3 −322.90228 0.3001.56093 36.6 4 −228.59270 2.100 1.80400 46.6 5 65.19707 0.200 1.00000 654.96083 5.379 2.00100 29.1 7 130.46571  D7 1.00000 8 127.91888 3.2001.59349 67.0 9 −2245.90430 1.780 1.00000 10 81.17716 3.500 1.69680 55.511 679.72724 2.453 1.00000 12 61.05134 5.724 1.59349 67.0 13 −130.200061.500 1.90366 31.3 14 46.24112 1.694 1.00000 15 77.95470 3.722 1.7725049.6 16 −564.05655 D16 1.00000 17 60.46759 5.400 1.80400 46.6 18−263.45861 D18 1.00000 19 (Aperture stop) 2.000 1.00000 20 −140.000001.178 1.77250 49.6 21 35.60000 4.059 1.00000 22 −35.16240 1.200 1.7291654.6 23 −51.36153 0.100 1.00000 24 69.55169 2.879 1.90200 25.3 25−209.71368 D25 1.00000 *26 −118.85935 1.100 1.77250 49.6 27 54.491351.415 1.00000 28 60.78441 2.635 1.90200 25.3 29 331.09581 D29 1.00000*30 118.81221 4.686 1.55332 71.7 31 −102.83315 0.100 1.00000 32152.27830 1.300 1.72000 28.0 33 85.35751 6.402 1.59319 67.9 34 −54.690930.188 1.00000 35 959.47501 7.222 1.49700 81.6 36 −30.23774 1.400 1.7060029.0 *37 1029.85760 D37 1.00000 38 53.49812 4.770 1.55332 71.7 39−6970.92580 1.400 1.90366 31.3 40 100.00000 D40 1.00000 [Aspheric Data]Surface κ A4 A6 A8 A10 2 −1.01100e−01 1.43852e−06 1.71179e−09−1.42870e−12 1.05723e−15 3 2.81381e+01 −7.54473e−07 4.14335e−10−5.77466e−13 3.16668e−16 26 −1.90000e+01 −9.14707e−07 9.49568e−100.00000e+00 0.00000e+00 30 −1.43460e+00 2.27762e−06 −5.51593e−100.00000e+00 0.00000e+00 37 2.44600e+03 4.05698e−06 0.00000e+000.00000e+00 0.00000e+00 [Various Data] W M T f 24.77 47.50 67.85 FNo2.90 2.90 2.91 ω 42.4 23.8 17.2 Y 21.60 21.60 21.60 TL 218.725 198.522200.695 BF 41.843 41.843 41.903 BF (air-conversion 41.843 41.843 41.903length) [Variable Distance Data] Focusing on infinity W M T D0 ∞ ∞ ∞Magnification — — — f 24.77 47.50 67.85 D7 49.003 12.690 1.835 D16 7.7507.750 7.750 D18 1.450 17.610 30.588 D25 1.473 1.473 1.473 D29 17.5198.681 1.500 D37 1.500 10.288 17.459 D40 41.843 41.843 41.903 [Lens GroupData] Lens group Starting surface Focal length 1st lens group 1 −38.882nd lens group 8 42.16 21st lens group 8 80.98 22nd lens group 17 61.633rd lens group 19 −42.05 31st lens group 19 −71.15 32nd lens group 26−121.45 4th lens group 30 56.98 5th lens group 38 619.99 [Focusing Data]W M T Lens moving 6.75 6.75 6.75 distance Imaging distance 0.4148 0.38650.4059 (m) [Conditional Expression Correspondence Values] ConditionalExpression (1) β(Gn)t = 6.597 Conditional Expression (2)−f(Gn~G(VR))w/fw = 1.698 Conditional Expression (3) f(RP)/f(FP) = 1.352Conditional Expression (4) ωt = 17.2 Conditional Expression (5) ωw =42.4

It is understood from Table 5 that the variable magnification opticalsystem ZL5 according to Example 5 satisfies Conditional Expressions (1)to (5).

FIG. 14 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL5 according to Example 5, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 15 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL5 according to Example 5 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 15.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL5 according to Example 5 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL5 has an excellent imaging performanceupon image blur correction.

Example 6

Example 6 will be described with reference to FIGS. 16 to 18 and Table6. As illustrated in FIG. 16, a variable magnification optical system ZL(ZL6) according to Example 6 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a positive refractive power, a fourth lens group G4 having anegative refractive power, a fifth lens group G5 having a negativerefractive power, a sixth lens group G6 having a positive refractivepower, and a seventh lens group G7 having a positive refractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 (a focusing lens group) is constituted by abiconvex lens L21, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25.

The third lens group G3 is constituted by a biconvex lens L31.

The fourth lens group G4 (an intermediate group) is constituted by, inorder from the object, an aperture stop S, a biconcave lens L41, anegative meniscus lens L42 having a concave surface oriented toward theobject side, and a biconvex lens L43, of which the positions in thedirection orthogonal to the optical axis are immovable.

The fifth lens group G5 (a vibration-reduction lens group) isconstituted by, in order from the object, a biconcave lens L51 and apositive meniscus lens L52 having a convex surface oriented toward theobject side. The biconcave lens L51 has an aspherical object-sidesurface.

The sixth lens group G6 is constituted by, in order from the object, abiconvex lens L61, a cemented lens including a negative meniscus lensL62 having a concave surface oriented toward the image side and abiconvex lens L63, and a cemented lens including a biconvex lens L64 anda biconcave lens L65. The biconvex lens L61 has an asphericalobject-side surface. The biconcave lens L65 has an aspherical image-sidesurface.

The seventh lens group G7 is constituted by a cemented lens including abiconvex lens L71 and a biconcave lens L72 arranged in that order fromthe object.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the object side, moving the fourth lens group G4toward the image side, moving the fifth lens group G5 toward the imageside and then moving the same toward the object side, and moving thesixth lens group G6 toward the object side such that the distancesbetween the respective lens groups are changed. The seventh lens groupG7 is immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the second lens group G2 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the fifth lens group G5 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 6, in the wide-angle end state, since the vibration reductioncoefficient is −0.46 and the focal length is 24.73 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.28 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.53 and the focallength is 47.48 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.48 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.58and the focal length is 67.41 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.61 mm.

Table 6 illustrates the values of respective specifications of Example6. Surface numbers 1 to 40 in Table 6 correspond to optical surfaces ofm1 to m40 illustrated in FIG. 16.

TABLE 6 [Lens Specification] Surface number R D n(d) νd 1 144.948172.900 1.74389 49.5 *2 29.83529 14.301 1.00000 *3 −322.90228 0.3001.56093 36.6 4 −228.59270 2.100 1.80400 46.6 5 65.19707 0.200 1.00000 654.96083 5.379 2.00100 29.1 7 130.46571  D7 1.00000 8 127.91888 3.2001.59349 67.0 9 −2245.90430 1.780 1.00000 10 81.17716 3.500 1.69680 55.511 679.72724 2.453 1.00000 12 61.05134 5.724 1.59349 67.0 13 −130.200061.500 1.90366 31.3 14 46.24112 1.694 1.00000 15 77.95470 3.722 1.7725049.6 16 −564.05655 D16 1.00000 17 60.46759 5.400 1.80400 46.6 18−263.45861 D18 1.00000 19 (Aperture stop) 2.000 1.00000 20 −140.000001.178 1.77250 49.6 21 35.60000 4.059 1.00000 22 −35.16240 1.200 1.7291654.6 23 −51.36153 0.100 1.00000 24 69.55169 2.879 1.90200 25.3 25−209.71368 D25 1.00000 *26 −118.85935 1.100 1.77250 49.6 27 54.491351.415 1.00000 28 60.78441 2.635 1.90200 25.3 29 331.09581 D29 1.00000*30 118.81221 4.686 1.55332 71.7 31 −102.83315 0.100 1.00000 32152.27830 1.300 1.72000 28.0 33 85.35751 6.402 1.59319 67.9 34 −54.690930.188 1.00000 35 959.47501 7.222 1.49700 81.6 36 −30.23774 1.400 1.7060029.0 *37 1029.85760 D37 1.00000 38 53.49812 4.770 1.55332 71.7 39−6970.92580 1.400 1.90366 31.3 40 100.00000 D40 1.00000 [Aspheric Data]Surface κ A4 A6 A8 A10 2 −1.01100e−01 1.43852e−06 1.71179e−09−1.42870e−12 1.05723e−15 3 2.81381e+01 −7.54473e−07 4.14335e−10−5.77466e−13 3.16668e−16 26 −1.90000e+01 −9.14707e−07 9.49568e−100.00000e+00 0.00000e+00 30 −1.43460e+00 2.27762e−06 −5.51593e−100.00000e+00 0.00000e+00 37 2.44600e+03 4.05698e−06 0.00000e+000.00000e+00 0.00000e+00 [Various Data] W M T f 24.73 47.48 67.41 FNo2.90 2.90 2.93 ω 42.5 23.9 17.3 Y 21.60 21.60 21.60 TL 218.388 200.467201.434 BF 41.880 42.603 42.530 BF (air-conversion length) 41.880 42.60342.530 [Variable Distance Data] Focusing on infinity W M T D0 ∞ ∞ ∞Magnification — — — f 24.73 47.48 67.41 D7 49.003 12.690 1.835 D16 7.7509.500 8.500 D18 1.450 17.000 30.000 D25 1.100 2.500 1.473 D29 17.5197.700 1.450 D37 1.500 10.288 17.459 D40 41.880 42.603 42.530 [Lens GroupData] Lens group Starting surface Focal length 1st lens group 1 −38.882nd lens group 8 80.98 3rd lens group 17 61.63 4th lens group 19 −71.155th lens group 26 −121.45 6th lens group 30 56.98 7th lens group 38619.99 [Focusing Data] W M T Lens moving 6.75 8.50 7.50 distance Imagingdistance 0.4145 0.3406 0.3816 (m) [Conditional Expression CorrespondenceValues] Conditional Expression (1) β(Gn)t = 6.868 Conditional Expression(2) −f(Gn~G(VR))w/fw = 1.704 Conditional Expression (3) f(RP)/f(FP) =1.352 Conditional Expression (4) ωt = 17.3 Conditional Expression (5) ωw= 42.5

It is understood from Table 6 that the variable magnification opticalsystem ZL6 according to Example 6 satisfies Conditional Expressions (1)to (5).

FIG. 17 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL6 according to Example 6, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 18 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL6 according to Example 6 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 18.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL6 according to Example 6 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL6 has an excellent imaging performanceupon image blur correction.

Example 7

Example 7 will be described with reference to FIGS. 19 to 21 and Table7. As illustrated in FIG. 19, a variable magnification optical system ZL(ZL7) according to Example 7 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a negative refractive power, a fourth lens group G4 having apositive refractive power, and a fifth lens group G5 having a positiverefractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, apositive meniscus lens L21 having a convex surface oriented toward theobject side, a biconvex lens L22, a biconcave lens L23, and a biconvexlens L24. The 22nd lens group G22 is constituted by a biconvex lens L25.

The third lens group G3 is constituted by, in order from the object, anaperture stop S, a 31st lens group G31 (an intermediate group) of whichthe position in the direction orthogonal to the optical axis isimmovable and which has negative refractive power and a 32nd lens groupG32 (a vibration-reduction lens group) having a negative refractivepower.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31, a negative meniscus lens L32 having a concavesurface oriented toward the object side, and a biconvex lens L33. The32nd lens group G32 is constituted by, in order from the object, abiconcave lens L34 and a positive meniscus lens L35 having a convexsurface oriented toward the object side. The biconcave lens L34 has anaspherical object-side surface.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a biconvex lens L42, and a cemented lens including abiconvex lens L43 and a biconcave lens L44. The biconvex lens L41 has anaspherical object-side surface.

The fifth lens group G5 is constituted by a cemented lens including, inorder from an object, a negative meniscus lens L51 having a concavesurface oriented toward the image side and a positive meniscus lens L52having a convex surface oriented toward the object side.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, and moving thefourth lens group G4 toward the object side such that the distancesbetween the respective lens groups are changed. The third lens group G3and the fifth lens group G5 are immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 7, in the wide-angle end state, since the vibration reductioncoefficient is −0.46 and the focal length is 24.77 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.29 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.52 and the focallength is 47.50 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.48 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.58and the focal length is 67.86 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.62 mm.

Table 7 illustrates the values of respective specifications of Example7. Surface numbers 1 to 38 in Table 7 correspond to optical surfaces ofm1 to m38 illustrated in FIG. 19.

TABLE 7 [Lens Specification] Surface number R D n(d) νd 1 155.896912.900 1.74389 49.5 *2 29.88191 12.307 1.00000 *3 −998.95016 0.3801.56093 36.6 4 −380.00000 2.100 1.75500 52.3 5 54.41504 0.200 1.00000 648.25639 5.777 1.90200 25.3 7 111.71017  D7 1.00000 8 75.52522 4.5001.75000 53.0 9 599.23665 3.427 1.00000 10 65.44832 4.500 1.75500 52.3 11−536.13486 0.864 1.00000 12 −161.64034 1.550 1.90200 25.3 13 48.600001.455 1.00000 14 77.92408 4.650 1.77250 49.6 15 −199.82321 D15 1.0000016 59.54554 5.676 1.81600 46.6 17 −305.53264 D17 1.00000 18 (Aperturestop) 2.000 1.00000 19 −140.00000 1.200 1.77250 49.6 20 34.07853 4.0221.00000 21 −34.00000 1.200 1.72916 54.6 22 −47.36695 0.100 1.00000 2360.05931 3.182 1.84666 23.8 24 −160.47286 D24 1.00000 *25 −266.901801.100 1.77250 49.6 26 80.68524 0.780 1.00000 27 68.16544 1.736 1.8466623.8 28 100.00000 D28 1.00000 *29 300.52804 4.082 1.55332 71.7 30−61.39111 0.100 1.00000 31 178.14990 4.513 1.60300 65.4 32 −65.353430.200 1.00000 33 142.59265 7.934 1.65160 58.6 34 −28.88978 1.400 1.9020029.1 35 300.00000 D35 1.00000 36 137.03160 1.400 1.83000 37.0 3764.66324 3.650 1.59319 67.9 38 735.00000 D38 1.00000 [Aspheric Data]Surface κ A4 A6 A8 A10 2 −9.54700e−01 5.69885e−06 −1.82979e−098.49633e−13 0.00000e+00 3 −1.40000e+01 −6.77491e−07 −2.49807e−100.00000e+00 0.00000e+00 25 −1.90000e+01 3.06942e−07 −6.70956e−100.00000e+00 0.00000e+00 29 5.86950e+00 −6.89526e−07 2.25877e−090.00000e+00 0.00000e+00 [Various Data] W M T f 24.77 47.50 67.86 FNo2.90 2.90 2.90 ω 42.4 23.9 17.2 Y 21.60 21.60 21.60 TL 210.992 190.994193.977 BF 39.982 39.983 40.044 BF (air-conversion 39.982 39.983 40.044length) [Variable Distance Data] Focusing on infinity W M T D0 ∞ ∞ ∞Magnification — — — f 24.77 47.50 67.86 D7 49.068 12.647 1.800 D15 7.7857.785 7.785 D17 3.346 19.816 33.635 D24 0.999 0.999 0.999 D28 19.42810.413 3.291 D35 1.500 10.465 17.538 D38 39.982 39.983 40.044 [LensGroup Data] Lens group Starting surface Focal length 1st lens group 1−38.96 2nd lens group 8 42.92 21st lens group 8 85.00 22nd lens group 1661.50 3rd lens group 18 −45.09 31st lens group 18 −84.08 32nd lens group25 −117.85 4th lens group 29 56.15 5th lens group 36 620.00 [FocusingData] W M T Lens moving 6.785 6.785 6.785 distance Imaging distance0.3997 0.3832 0.4060 (m) [Conditional Expression Correspondence Values]Conditional Expression (1) β(Gn)t = 4.299 Conditional Expression (2)−f(Gn~G(VR))w/fw = 1.820 Conditional Expression (3) f(RP)/f(FP) = 1.308Conditional Expression (4) ωt = 17.2 Conditional Expression (5) ωw =42.4

It is understood from Table 7 that the variable magnification opticalsystem ZL7 according to Example 7 satisfies Conditional Expressions (1)to (5).

FIG. 20 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL7 according to Example 7, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 21 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL7 according to Example 7 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 21.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL7 according to Example 7 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL7 has an excellent imaging performanceupon image blur correction.

Example 8

Example 8 will be described with reference to FIGS. 22 to 24 and Table8. As illustrated in FIG. 22, a variable magnification optical system ZL(ZL8) according to Example 8 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a negative refractive power, a fourth lens group G4 having apositive refractive power, and a fifth lens group G5 having a positiverefractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface. The biconcavelens L12 is a composite aspherical lens obtained by forming a resinlayer formed on a glass surface on the object side into an asphericalsurface.

The second lens group G2 is constituted by, in order from the object, aflare-cut diaphragm FC, a 21st lens group G21 (a focusing lens group)having a positive refractive power and a 22nd lens group G22 having apositive refractive power.

The 21st lens group G21 is constituted by, in order from the object, apositive meniscus lens L21 having a convex surface oriented toward theobject side, a biconvex lens L22, a biconcave lens L23, and a biconvexlens L24. The 22nd lens group G22 is constituted by a biconvex lens L25.

The third lens group G3 is constituted by, in order from the object, anaperture stop S, a 31st lens group G31 (an intermediate group) of whichthe position in the direction orthogonal to the optical axis isimmovable and which has negative refractive power and a 32nd lens groupG32 (a vibration-reduction lens group) having a negative refractivepower.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31, a negative meniscus lens L32 having a concavesurface oriented toward the object side, and a biconvex lens L33. The32nd lens group G32 is constituted by, in order from the object, abiconcave lens L34 and a positive meniscus lens L35 having a convexsurface oriented toward the object side. The biconcave lens L34 has anaspherical object-side surface.

The fourth lens group G4 is constituted by, in order from the object, apositive meniscus lens L41 having a convex surface oriented toward theimage side, a biconvex lens L42, and a cemented lens including abiconvex lens L43 and a biconcave lens L44. The positive meniscus lensL41 has an aspherical object-side surface.

The fifth lens group G5 is constituted by a cemented lens including, inorder from an object, a negative meniscus lens L51 having a concavesurface oriented toward the image side and a positive meniscus lens L52having a convex surface oriented toward the object side.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, and moving thefourth lens group G4 toward the object side such that the distancesbetween the respective lens groups are changed. The third lens group G3and the fifth lens group G5 are immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 8, in the wide-angle end state, since the vibration reductioncoefficient is −0.50 and the focal length is 24.77 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.26 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.58 and the focallength is 47.50 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.43 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.66and the focal length is 67.85 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.54 mm.

Table 8 illustrates the values of respective specifications of Example8. Surface numbers 1 to 39 in Table 8 correspond to optical surfaces ofm1 to m39 illustrated in FIG. 22.

TABLE 8 [Lens Specification] Surface number R D n(d) νd 1 171.223782.900 1.74389 49.5 *2 29.77139 12.208 1.00000 *3 −2272.73400 0.3801.56093 36.6 4 −400.00000 2.100 1.75500 52.3 5 59.96509 0.200 1.00000 650.35816 7.000 1.90200 25.3 7 111.56759  D7 1.00000 8 0.00000 0.2001.00000 9 82.35931 3.100 1.75000 51.0 10 869.55661 3.243 1.00000 1165.70660 4.150 1.77250 49.6 12 −400.15117 0.889 1.00000 13 −142.768031.550 1.90200 25.3 14 49.72103 1.379 1.00000 15 78.21406 4.000 1.7725049.6 16 −195.63433 D16 1.00000 17 58.26284 5.676 1.81600 46.6 18−346.07444 D18 1.00000 19 (Aperture stop) 2.000 1.00000 20 −140.000001.200 1.77250 49.6 21 36.40792 4.110 1.00000 22 −39.80791 1.200 1.7291654.7 23 −59.45079 0.100 1.00000 24 69.32659 3.085 1.84666 23.8 25−134.48153 D25 1.00000 *26 −251.99331 1.100 1.77250 49.6 27 63.185000.868 1.00000 28 59.71324 2.131 1.86000 24.2 29 100.00000 D29 1.00000*30 −900.00000 3.663 1.55332 71.7 31 −54.18440 0.100 1.00000 32 84.946395.806 1.60300 65.5 33 −60.43832 0.200 1.00000 34 278.20778 6.810 1.6516058.5 35 −32.56689 1.400 1.90200 28.5 36 191.68646 D36 1.00000 37132.64391 1.400 1.83000 34.0 38 61.28313 3.734 1.59319 67.9 39 735.00000D39 1.00000 [Aspheric Data] Surface κ A4 A6 A8 A10 2 −3.84000e−012.66465e−06 −1.34312e−10 −5.72743e−14 0.00000e+00 3 3.50000e+00−9.48227e−07 −3.38888e−10 0.00000e+00 0.00000e+00 26 −2.80000e+013.11252e−07 −7.78416e−10 0.00000e+00 0.00000e+00 30 −6.00000e+00−1.99894e−06 1.27933e−09 0.00000e+00 0.00000e+00 [Various Data] W M T f24.77 47.50 67.85 FNo 2.90 2.90 2.90 ω 42.4 24.0 17.2 Y 21.60 21.6021.60 TL 209.253 187.862 189.544 BF 40.016 40.020 40.085 BF(air-conversion length) 40.016 40.020 40.085 [Variable Distance Data]Focusing on infinity W M T D0 ∞ ∞ ∞ Magnification — — — f 24.77 47.5067.85 D7 49.018 12.518 1.800 D16 7.835 7.835 7.835 D18 3.200 18.35530.700 D25 0.930 0.930 0.930 D29 18.873 9.373 1.900 D36 1.500 10.95018.413 D39 40.016 40.020 40.085 [Lens Group Data] Lens group Startingsurface Focal length 1st lens group 1 −39.60 2nd lens group 8 41.35 21stlens group 8 84.99 22nd lens group 17 61.50 3rd lens group 19 −43.4431st lens group 19 −85.70 32nd lens group 26 −106.03 4th lens group 3054.89 5th lens group 37 619.95 [Focusing Data] W M T Lens moving 6.8356.835 6.835 distance Imaging distance 0.4055 0.3839 0.4040 (m)[Conditional Expression Correspondence Values] Conditional Expression(1) β(Gn)t = 3.949 Conditional Expression (2) −f(Gn~G(VR))w/fw = 1.754Conditional Expression (3) f(RP)/f(FP) = 1.327 Conditional Expression(4) ωt = 17.2 Conditional Expression (5) ωw = 42.4

It is understood from Table 8 that the variable magnification opticalsystem ZL8 according to Example 8 satisfies Conditional Expressions (1)to (5).

FIG. 23 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL8 according to Example 8, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 24 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL8 according to Example 8 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 24.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL8 according to Example 8 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL8 has an excellent imaging performanceupon image blur correction.

Example 9

Example 9 will be described with reference to FIGS. 25 to 27 and Table9. As illustrated in FIG. 25, a variable magnification optical system ZL(ZL9) according to Example 9 is constituted by, in order from an object,a first lens group G1 having a negative refractive power, a second lensgroup G2 having a positive refractive power, a third lens group G3having a negative refractive power, a fourth lens group G4 having apositive refractive power, and a fifth lens group G5 having a positiverefractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a positive meniscus lens L13having a convex surface oriented toward the object side. The negativemeniscus lens L11 has an aspherical image-side surface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, abiconvex lens L21, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25. The 22ndlens group G22 is constituted by a cemented lens including, in orderfrom an object, a biconvex lens L26 and a negative meniscus lens L27having a concave surface oriented toward the object side.

The third lens group G3 is constituted by, in order from the object, a31st lens group G31 (an intermediate group) of which the position in thedirection orthogonal to the optical axis is immovable and which hasnegative refractive power and a 32nd lens group G32 (avibration-reduction lens group) having a negative refractive power.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31, a negative meniscus lens L32 having a concavesurface oriented toward the object side, and a positive meniscus lensL33 having a convex surface oriented toward the image side. The 32ndlens group G32 is constituted by, in order from the object, a biconcavelens L34 and a biconvex lens L35. The biconcave lens L34 has anaspherical surface on both sides thereof.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a biconvex lens L42, and a cemented lens including abiconvex lens L43 and a biconcave lens L44. The biconvex lens L41 has anaspherical object-side surface. The biconcave lens L44 has an asphericalimage-side surface.

The fifth lens group G5 is constituted by a cemented lens including abiconvex lens L51 and a biconcave lens L52 arranged in that order fromthe object.

An aperture stop S is disposed between the second lens group G2 and thethird lens group G3.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the image side and then moving the same toward theobject side, and moving the fourth lens group G4 toward the object sidesuch that the distances between the respective lens groups are changed.The fifth lens group G5 and the aperture stop S are immovable uponvarying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 9, in the wide-angle end state, since the vibration reductioncoefficient is −0.51 and the focal length is 24.77 mm, the movingdistance of the vibration-reduction lens group VR for correcting therotation blur of 0.30° is −0.25 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.57 and the focallength is 47.50 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.43 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.66and the focal length is 67.85 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.54 mm.

Table 9 illustrates the values of respective specifications of Example9. Surface numbers 1 to 39 in Table 9 correspond to optical surfaces ofm1 to m39 illustrated in FIG. 25.

TABLE 9 [Lens Specification] Surface number R D n(d) νd 1 180.280312.900 1.74389 49.5 *2 30.43353 15.281 1.00000 3 −400.00000 2.100 1.8040046.6 4 61.64102 0.200 1.00000 5 52.74108 5.413 2.00100 29.1 6 127.21255 D6 1.00000 7 250.61095 3.650 1.48749 70.3 8 −249.39202 0.258 1.00000 960.71776 3.347 1.69680 55.5 10 223.73133 2.543 1.00000 11 88.72642 4.0521.59349 67.0 12 −200.28776 1.450 1.90366 31.3 13 46.94856 1.456 1.0000014 71.21863 4.324 1.77250 49.6 15 −259.88006 D15 1.00000 16 64.616435.373 1.80400 46.6 17 −171.33576 1.500 1.85026 32.4 18 −427.99181 D181.00000 19 (Aperture stop) D19 1.00000 20 −140.00000 1.200 1.77250 49.621 98.73269 2.349 1.00000 22 −46.53449 1.200 1.76000 50.0 23 −88.625730.100 1.00000 24 −227.14142 2.169 1.90200 25.3 25 −65.70168 D25 1.00000*26 −82.31022 1.100 1.77250 49.6 *27 41.14809 1.433 1.00000 28 50.515933.020 1.90200 25.3 29 −7587.28970 D29 1.00000 *30 445.83969 3.9661.55332 71.7 31 −73.29859 0.100 1.00000 32 153.51046 3.949 1.60300 65.433 −101.27922 0.200 1.00000 34 86.09865 7.212 1.59319 67.9 35 −40.793051.200 1.79000 26.0 *36 180.00000 D36 1.00000 37 69.32616 4.432 1.6180063.3 38 −225.96343 1.200 1.90366 31.3 39 140.29946 D39 1.00000 [AsphericData] Surface κ A4 A6 A8 A10 2 −1.14500e−01 2.30934e−06 4.18972e−106.24631e−13 0.00000e+00 26 −4.22870e+00 4.95698e−23 1.31315e−090.00000e+00 0.00000e+00 27 5.80700e−01 3.38518e−07 0.00000e+000.00000e+00 0.00000e+00 30 1.94200e−01 3.81661e−06 −2.35375e−090.00000e+00 0.00000e+00 36 1.00000e+00 4.12000e−06 0.00000e+000.00000e+00 0.00000e+00 [Various Data] W M T f 24.77 47.50 67.85 FNo2.90 2.90 2.92 ω 42.3 23.9 17.2 Y 21.60 21.60 21.60 TL 214.110 194.068198.548 BF 40.318 40.318 40.378 BF (air-conversion length) 40.318 40.31840.378 [Variable Distance Data] Focusing on infinity W M T D0 ∞ ∞ ∞Magnification — — — f 24.77 47.50 67.85 D6 49.013 12.596 1.845 D15 7.8407.840 7.840 D18 3.000 19.375 34.606 D19 2.000 3.243 2.000 D25 0.9300.930 0.930 D29 20.833 9.633 1.900 D36 1.500 11.458 20.373 D39 40.31840.318 40.378 [Lens Group Data] Lens group Starting surface Focal length1st lens group 1 −39.13 2nd lens group 7 43.78 21st lens group 7 80.9722nd lens group 16 71.04 3rd lens group 20 −48.53 31st lens group 20−95.21 32nd lens group 26 −105.72 4th lens group 30 57.82 5th lens group37 700.00 [Focusing Data] W M T Lens moving 6.840 6.840 6.840 distanceImaging distance 0.4165 0.3788 0.3972 (m) [Conditional ExpressionCorrespondence Values] Conditional Expression (1) β(Gn)t = 3.341Conditional Expression (2) −f(Gn~G(VR))w/fw = 1.959 ConditionalExpression (3) f(RP)/f(FP) = 1.321 Conditional Expression (4) ωt = 17.2Conditional Expression (5) ωw = 42.3

It is understood from Table 9 that the variable magnification opticalsystem ZL9 according to Example 9 satisfies Conditional Expressions (1)to (5).

FIG. 26 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL9 according to Example 9, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 27 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL9 according to Example 9 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 27.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL9 according to Example 9 hasa satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL9 has an excellent imaging performanceupon image blur correction.

Example 10

Example 10 will be described with reference to FIGS. 28 to 30 and Table10. As illustrated in FIG. 28, a variable magnification optical systemZL (ZL10) according to Example 10 is constituted by, in order from anobject, a first lens group G1 having a negative refractive power, asecond lens group G2 having a positive refractive power, a third lensgroup G3 having a negative refractive power, a fourth lens group G4having a positive refractive power, and a fifth lens group G5 having apositive refractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a cemented lens including a positive meniscus lens L12having a convex surface oriented toward the object side and a biconcavelens L13, and a positive meniscus lens L14 having a convex surfaceoriented toward the object side. The negative meniscus lens L11 has anaspherical image-side surface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, apositive meniscus lens L21 having a convex surface oriented toward theobject side, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a cemented lens including a biconvexlens L23 and a biconcave lens L24, and a biconvex lens L25. The 22ndlens group G22 is constituted by a biconvex lens L26. The positivemeniscus lens L22 has an aspherical object-side surface.

The third lens group G3 is constituted by, in order from the object, anaperture stop S, a 31st lens group G31 (an intermediate group) of whichthe position in the direction orthogonal to the optical axis isimmovable and which has negative refractive power and a 32nd lens groupG32 (a vibration-reduction lens group) having a negative refractivepower.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side. The 32nd lens group G32 isconstituted by, in order from the object, a biconcave lens L33 and apositive meniscus lens L34 having a convex surface oriented toward theobject side. The biconcave lens L33 has an aspherical object-sidesurface.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a cemented lens including a negative meniscus lensL42 having a concave surface oriented toward the image side and abiconvex lens L43, and a cemented lens including a biconvex lens L44 anda biconcave lens L45. The biconvex lens L41 has an asphericalobject-side surface. The biconcave lens L45 has an aspherical image-sidesurface.

The fifth lens group G5 is constituted by a cemented lens including, inorder from an object, a positive meniscus lens L51 having a convexsurface oriented toward the object side and a negative meniscus lens L52having a concave surface oriented toward the image side arranged.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the image side and then moving the same toward theobject side, and moving the fourth lens group G4 toward the object sidesuch that the distances between the respective lens groups are changed.The fifth lens group G5 is immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 10, in the wide-angle end state, since the vibrationreduction coefficient is −0.50 and the focal length is 24.77 mm, themoving distance of the vibration-reduction lens group VR for correctingthe rotation blur of 0.30° is −0.26 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.57 and the focallength is 47.50 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.44 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.66and the focal length is 67.84 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.54 mm.

Table 10 illustrates the values of respective specifications of Example10. Surface numbers 1 to 38 in Table 10 correspond to optical surfacesof m1 to m38 illustrated in FIG. 28.

TABLE 10 [Lens Specification] Surface number R D n(d) νd 1 179.735292.880 1.74389 49.5 *2 28.00000 13.314 1.00000 3 −709.59863 2.295 1.8051825.4 4 −228.05154 2.100 1.76500 49.5 5 90.21469 0.200 1.00000 6 56.000204.396 2.00100 29.1 7 96.29881  D7 1.00000 8 96.54068 2.840 1.60300 65.49 715.47283 0.200 1.00000 *10 57.08059 3.395 1.69680 55.5 11 181.189285.604 1.00000 12 98.04986 3.261 1.59319 67.9 13 −796.91447 1.450 1.7618226.6 14 41.75300 1.983 1.00000 15 73.03256 3.630 1.74100 52.8 16−3863.66610 D16 1.00000 17 58.79270 5.010 1.80400 46.6 18 −393.67543 D181.00000 19 (Aperture stop) 1.540 1.00000 20 −142.34068 1.200 1.8160046.6 21 35.05467 1.301 1.00000 22 38.87328 2.715 1.90200 25.3 23117.88926 D23 1.00000 *24 −118.17706 1.200 1.73231 53.2 25 44.697441.030 1.00000 26 52.10387 2.485 1.90200 25.3 27 195.76461 D27 1.00000*28 71.27465 4.998 1.49782 82.6 29 −102.88416 0.100 1.00000 30 91.682691.200 1.90366 31.3 31 52.62629 6.605 1.60300 65.4 32 −69.88439 0.2001.00000 33 3314.77510 4.235 1.59319 67.9 34 −54.08421 1.200 1.78500 26.2*35 216.08233 D35 1.00000 36 56.19817 3.548 1.61800 63.3 37 210.950971.200 1.83400 37.2 38 84.00000 D38 1.00000 [Aspheric Data] Surface κ A4A6 A8 A10 2 −6.73000e−02 2.59588e−06 7.45638e−10 −2.10470e−143.51745e−16 10 1.00000e+00 −4.00000e−07 0.00000e+00 0.00000e+000.00000e+00 24 −4.10880e+00 5.35515e−07 2.05353e−09 0.00000e+000.00000e+00 28 −1.10460e+00 3.84373e−06 −4.29919e−09 3.81283e−120.00000e+00 35 1.00000e+00 5.16409e−06 2.00000e−09 0.00000e+000.00000e+00 [Various Data] W M T f 24.77 47.50 67.84 FNo 2.90 2.90 2.90ω 42.2 23.9 17.2 Y 21.60 21.60 21.60 TL 208.124 187.432 190.017 BF40.315 40.322 40.381 BF (air-conversion 40.315 40.322 40.381 length)[Variable Distance Data] Focusing on infinity W M T D0 ∞ ∞ ∞Magnification — — — f 24.77 47.50 67.84 D7 48.968 12.510 1.800 D16 7.1857.185 7.185 D18 1.300 17.853 29.355 D23 2.232 2.232 2.232 D27 19.3119.731 1.900 D35 1.500 10.287 19.851 D38 40.315 40.322 40.381 [Lens GroupData] Lens group Starting surface Focal length 1st lens group 1 −39.972nd lens group 8 43.09 21st lens group 8 80.97 22nd lens group 17 63.943rd lens group 19 −42.99 31st lens group 19 −77.20 32nd lens group 24−103.89 4th lens group 28 56.10 5th lens group 36 419.32 [Focusing Data]W M T Lens moving distance 6.185 6.185 6.185 Imaging distance (m) 0.44440.4101 0.4308 [Conditional Expression Correspondence Values] ConditionalExpression (1) β(Gn)t = 4.359 Conditional Expression (2)−f(Gn~G(VR))w/fw = 1.736 Conditional Expression (3) f(RP)/f(FP) = 1.302Conditional Expression (4) ωt = 17.2 Conditional Expression (5) ωw =42.2

It is understood from Table 10 that the variable magnification opticalsystem ZL10 according to Example 10 satisfies Conditional Expressions(1) to (5).

FIG. 29 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL10 according to Example 10, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 30 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL10 according to Example 10 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 30.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL10 according to Example 10has a satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL10 has an excellent imaging performanceupon image blur correction.

Example 11

Example 11 will be described with reference to FIGS. 31 to 33 and Table11. As illustrated in FIG. 31, a variable magnification optical systemZL (ZL11) according to Example 11 is constituted by, in order from anobject, a first lens group G1 having a negative refractive power, asecond lens group G2 having a positive refractive power, a third lensgroup G3 having a negative refractive power, a fourth lens group G4having a positive refractive power, and a fifth lens group G5 having apositive refractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a cemented lens including apositive meniscus lens L13 having a convex surface oriented toward theobject side and a negative meniscus lens L14 having a concave surfaceoriented toward the image side. The negative meniscus lens L11 has anaspherical image-side surface.

The second lens group G2 is constituted by, in order from the object, a21st lens group G21 (a focusing lens group) having a positive refractivepower and a 22nd lens group G22 having a positive refractive power.

The 21st lens group G21 is constituted by, in order from the object, apositive meniscus lens L21 having a convex surface oriented toward theobject side, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a negative meniscus lens L23 having aconcave surface oriented toward the image side, and a biconvex lens L24.The 22nd lens group G22 is constituted by a cemented lens including, inorder from an object, a negative meniscus lens L25 having a concavesurface oriented toward the image side and a biconvex lens L26. Thepositive meniscus lens L22 has an aspherical object-side surface.

The third lens group G3 is constituted by, in order from the object, anaperture stop S, a 31st lens group G31 (an intermediate group) of whichthe position in the direction orthogonal to the optical axis isimmovable and which has negative refractive power and a 32nd lens groupG32 (a vibration-reduction lens group) having a negative refractivepower.

The 31st lens group G31 is constituted by, in order from the object, abiconcave lens L31 and a positive meniscus lens L32 having a convexsurface oriented toward the object side. The 32nd lens group G32 isconstituted by, in order from the object, a biconcave lens L33 and apositive meniscus lens L34 having a convex surface oriented toward theobject side. The biconcave lens L33 has an aspherical object-sidesurface.

The fourth lens group G4 is constituted by, in order from the object, abiconvex lens L41, a positive meniscus lens L42 having a convex surfaceoriented toward the image side, and a cemented lens including a negativemeniscus lens L43 having a concave surface oriented toward the imageside and a biconvex lens L44. The biconvex lens L44 has an asphericalimage-side surface.

The fifth lens group G5 is constituted by a cemented lens including, inorder from an object, a positive meniscus lens L51 having a convexsurface oriented toward the object side and a negative meniscus lens L52having a concave surface oriented toward the image side.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the image side and then moving the same toward theobject side, and moving the fourth lens group G4 toward the object sidesuch that the distances between the respective lens groups are changed.The fifth lens group G5 is immovable upon varying magnification.

Focusing from an object at infinity to an object at a close distance isperformed by moving the 21st lens group G21 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the 32nd lens group G32 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 11, in the wide-angle end state, since the vibrationreduction coefficient is −0.54 and the focal length is 24.77 mm, themoving distance of the vibration-reduction lens group VR for correctingthe rotation blur of 0.30° is −0.24 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.61 and the focallength is 47.53 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.41 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.70and the focal length is 67.85 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.51 mm.

Table 11 illustrates the values of respective specifications of Example11. Surface numbers 1 to 37 in Table 11 correspond to optical surfacesof m1 to m37 illustrated in FIG. 31.

TABLE 11 [Lens Specification] Surface number R D n(d) νd 1 169.823922.880 1.74389 49.5 *2 28.00000 13.823 1.00000 3 −277.92141 2.100 1.6968055.5 4 89.48130 0.972 1.00000 5 57.53130 5.977 1.90366 31.3 6 288.247202.000 1.60311 60.7 7 89.16103  D7 1.00000 8 97.98839 2.906 1.62041 60.39 988.16122 0.870 1.00000 *10 52.75776 3.799 1.69680 55.5 11 185.818173.941 1.00000 12 244.48174 1.450 1.74077 27.7 13 42.81836 2.225 1.0000014 81.99098 3.910 1.74100 52.8 15 −359.52152 D15 1.00000 16 56.225251.450 1.85000 25.5 17 41.20061 6.609 1.75500 52.3 18 −333.94984 D181.00000 19 (Aperture stop) 1.488 1.00000 20 −133.09742 1.200 1.8160046.6 21 40.80390 0.998 1.00000 22 48.84393 2.545 1.90200 25.3 23197.19167 D23 1.00000 *24 −159.18908 1.200 1.70000 55.0 25 46.354020.845 1.00000 26 47.53111 2.169 1.90200 25.3 27 92.34748 D27 1.00000 2859.48521 4.431 1.59319 67.9 29 −192.71174 0.100 1.00000 30 −6013.334103.364 1.59319 67.9 31 −71.43167 0.200 1.00000 32 5300.14030 1.4041.90366 31.3 33 31.44019 7.197 1.59319 67.9 *34 −117.32485 D34 1.0000035 57.67894 3.814 1.70000 56.0 36 263.45851 0.763 1.77250 49.6 3784.00000 D37 1.00000 [Aspheric Data] Surface κ A4 A6 A8 A10 2−5.97000e−02 2.62042e−06 7.82559e−10 9.78767e−14 4.33213e−16 105.28200e−01 6.32647e−08 1.88164e−10 0.00000e+00 0.00000e+00 24−6.74850e+00 4.82591e−07 2.86667e−10 0.00000e+00 0.00000e+00 34−1.67545e+01 1.36811e−06 3.39381e−09 0.00000e+00 0.00000e+00 [VariousData] W M T f 24.77 47.53 67.85 FNo 2.90 2.90 2.91 ω 42.2 23.9 17.3 Y21.60 21.60 21.60 TL 210.949 190.232 192.480 BF 43.417 43.503 43.670 BF(air-conversion length) 43.417 43.503 43.670 [Variable Distance Data]Focusing on infinity W M T D0 ∞ ∞ ∞ Magnification — — — f 24.77 47.5367.85 D7 48.868 12.444 1.800 D15 7.185 7.185 7.185 D18 0.800 16.87228.207 D23 1.827 1.827 1.827 D27 20.646 10.368 1.900 D34 1.574 11.40121.260 D37 43.417 43.503 43.670 [Lens Group Data] Lens group Startingsurface Focal length 1st lens group 1 −39.52 2nd lens group 8 42.67 21stlens group 8 81.00 22nd lens group 16 66.83 3rd lens group 19 −43.8431st lens group 19 −83.74 32nd lens group 24 −98.45 4th lens group 2861.94 5th lens group 35 285.15 [Focusing Data] W M T Lens moving 6.1856.185 6.185 distance Imaging distance 0.4485 0.4038 0.4202 (m)[Conditional Expression Correspondence Values] Conditional Expression(1) β(Gn)t = 3.303 Conditional Expression (2) −f(Gn~G(VR))w/fw = 1.771Conditional Expression (3) f(RP)/f(FP) = 1.452 Conditional Expression(4) ωt = 17.3 Conditional Expression (5) ωw = 42.2

It is understood from Table 11 that the variable magnification opticalsystem ZL11 according to Example 11 satisfies Conditional Expressions(1) to (5).

FIG. 32 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL11 according to Example 11, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 33 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL11 according to Example 11 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±15.10 about the image height y=0.0 as illustrated inFIG. 33.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL11 according to Example 11has a satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL11 has an excellent imaging performanceupon image blur correction.

Example 12

Example 12 will be described with reference to FIGS. 34 to 36 and Table12. As illustrated in FIG. 34, a variable magnification optical systemZL (ZL12) according to Example 12 is constituted by, in order from anobject, a first lens group G1 having a negative refractive power, asecond lens group G2 having a positive refractive power, a third lensgroup G3 having a positive refractive power, a fourth lens group G4having a negative refractive power, a fifth lens group G5 having anegative refractive power, a sixth lens group G6 having a positiverefractive power, and a seventh lens group G7 having a positiverefractive power.

The first lens group G1 is constituted by, in order from the object, anegative meniscus lens L11 having a concave surface oriented toward theimage side, a biconcave lens L12, and a cemented lens including apositive meniscus lens L13 having a convex surface oriented toward theobject side and a negative meniscus lens L14 having a concave surfaceoriented toward the image side. The negative meniscus lens L11 has anaspherical image-side surface.

The second lens group G2 (focusing lens group) is constituted by apositive meniscus lens L21 having a convex surface oriented toward theobject side, a positive meniscus lens L22 having a convex surfaceoriented toward the object side, a negative meniscus lens L23 having aconcave surface oriented toward the image side, and a biconvex lens L24.The positive meniscus lens L22 has an aspherical object-side surface.

The third lens group G3 is constituted by a cemented lens including, inorder from an object, a negative meniscus lens L31 having a concavesurface oriented toward the image side and a biconvex lens L32.

The fourth lens group G4 (intermediate group) is constituted by, inorder from the object, an aperture stop S, a biconcave lens L41, and apositive meniscus lens L42 having a convex surface oriented toward theobject side of which the positions in the direction orthogonal to theoptical axis are immovable.

The fifth lens group G5 (a vibration-reduction lens group) isconstituted by, in order from the object, a biconcave lens L51 and apositive meniscus lens L52 having a convex surface oriented toward theobject side. The biconcave lens L51 has an aspherical object-sidesurface.

The sixth lens group G6 is constituted by, in order from the object, abiconvex lens L61, a positive meniscus lens L62 having a concave surfaceoriented toward the image side, and a cemented lens including and anegative meniscus lens L63 having a concave surface oriented toward theimage side and a biconvex lens L64. The biconcave lens L64 has anaspherical image-side surface.

The seventh lens group G7 is constituted by a cemented lens including,in order from an object, a positive meniscus lens L71 having a convexsurface oriented toward the object side and a negative meniscus lens L72having a concave surface oriented toward the image side.

Varying magnification from the wide-angle end state to the telephoto endstate is performed by moving the first lens group G1 toward the imageside and then moving the first lens group G1 toward the object side,moving the second lens group G2 toward the object side, moving the thirdlens group G3 toward the object side, moving the fourth lens group G4toward the image side and then moving the same toward the object side,moving the fifth lens group G5 toward the image side and then moving thesame toward the object side, moving the sixth lens group G6 toward theobject side, and moving the seventh lens group G7 toward the object sidesuch that the distances between the respective lens groups are changed.

Focusing from an object at infinity to an object at a close distance isperformed by moving the second lens group G2 as a focusing lens grouptoward the image side.

When image blur occurs, image blur correction (vibration reduction) onthe image plane I is performed by moving the fifth lens group G5 as thevibration-reduction lens group VR so as to have a component in thedirection orthogonal to the optical axis. In an image capturing lens inwhich the focal length of an entire system is f and a vibrationreduction coefficient (the ratio of an image moving distance on animaging plane to a moving distance of a moving lens group during blurcorrection) is K, in order to correct rotation blur of angle θ, thevibration-reduction lens group VR (a moving lens group) for image blurcorrection may be moved in the direction orthogonal to the optical axisby (f×tan θ)/K.

In Example 12, in the wide-angle end state, since the vibrationreduction coefficient is −0.54 and the focal length is 24.77 mm, themoving distance of the vibration-reduction lens group VR for correctingthe rotation blur of 0.30° is −0.24 mm. In the intermediate focal lengthstate, since the vibration reduction coefficient is −0.61 and the focallength is 47.33 mm, the moving distance of the vibration-reduction lensgroup VR for correcting the rotation blur of 0.30° is −0.41 mm. In thetelephoto end state, since the vibration reduction coefficient is −0.72and the focal length is 67.34 mm, the moving distance of thevibration-reduction lens group VR for correcting the rotation blur of0.30° is −0.50 mm.

Table 12 illustrates the values of respective specifications of Example12. Surface numbers 1 to 37 in Table 12 correspond to optical surfacesof m1 to m37 illustrated in FIG. 34.

TABLE 12 [Lens Specification] Surface number R D n(d) νd 1 169.823922.880 1.74389 49.5 *2 28.00000 13.823 1.00000 3 −277.92141 2.100 1.6968055.5 4 89.48130 0.972 1.00000 5 57.53130 5.977 1.90366 31.3 6 288.247202.000 1.60311 60.7 7 89.16103  D7 1.00000 8 97.98839 2.906 1.62041 60.39 988.16122 0.870 1.00000 *10 52.75776 3.799 1.69680 55.5 11 185.818173.941 1.00000 12 244.48174 1.450 1.74077 27.7 13 42.81836 2.225 1.0000014 81.99098 3.910 1.74100 52.8 15 −359.52152 D15 1.00000 16 56.225251.450 1.85000 25.5 17 41.20061 6.609 1.75500 52.3 18 −333.94984 D181.00000 19 (Aperture stop) 1.488 1.00000 20 −133.09742 1.200 1.8160046.6 21 40.80390 0.998 1.00000 22 48.84393 2.545 1.90200 25.3 23197.19167 D23 1.00000 *24 −159.18908 1.200 1.70000 55.0 25 46.354020.845 1.00000 26 47.53111 2.169 1.90200 25.3 27 92.34748 D27 1.00000 2859.48521 4.431 1.59319 67.9 29 −192.71174 0.100 1.00000 30 −6013.334103.364 1.59319 67.9 31 −71.43167 0.200 1.00000 32 5300.14030 1.4041.90366 31.3 33 31.44019 7.197 1.59319 67.9 *34 −117.32485 D34 1.0000035 57.67894 3.814 1.70000 56.0 36 263.45851 0.763 1.77250 49.6 3784.00000 D37 1.00000 [Aspheric Data] Surface κ A4 A6 A8 A10 2−5.97000e−02 2.62042e−06 7.82559e−10 9.78767e−14 4.33213e−16 105.28200e−01 6.32647e−08 1.88164e−10 0.00000e+00 0.00000e+00 24−6.74850e+00 4.82591e−07 2.86667e−10 0.00000e+00 0.00000e+00 34−1.67545e+01 1.36811e−06 3.39381e−09 0.00000e+00 0.00000e+00 [VariousData] W M T f 24.77 47.33 67.34 FNo 2.90 2.90 2.91 ω 42.2 24.0 17.4 Y21.60 21.60 21.60 TL 210.949 193.610 195.380 BF 43.417 43.433 45.688 BF(air-conversion length) 43.417 43.433 45.688 [Variable Distance Data]Focusing on infinity W M T D0 ∞ ∞ ∞ Magnification — — — f 24.77 47.3367.34 D7 48.868 12.444 1.600 D15 7.185 12.000 9.500 D18 0.800 16.87226.900 D23 1.827 1.827 2.000 D27 20.646 9.000 1.800 D34 1.574 11.40121.260 D37 43.417 43.433 45.688 [Lens Group Data] Lens group Startingsurface Focal length 1st lens group 1 −39.52 2nd lens group 8 81.00 3rdlens group 16 66.83 4th lens group 19 −83.74 5th lens group 24 −98.456th lens group 28 61.94 7th lens group 35 285.15 [Focusing Data] W M TLens moving 6.185 11.000 8.500 distance Imaging distance 0.4485 0.29460.3494 (m) [Conditional Expression Correspondence Values] ConditionalExpression (1) β(Gn)t = 3.516 Conditional Expression (2)−f(Gn~G(VR))w/fw = 1.770 Conditional Expression (3) f(RP)/f(FP) = 1.452Conditional Expression (4) ωt = 17.4 Conditional Expression (5) ωw =42.2

It is understood from Table 12 that the variable magnification opticalsystem ZL12 according to Example 12 satisfies Conditional Expressions(1) to (5).

FIG. 35 shows graphs illustrating various aberrations (sphericalaberration, astigmatism, distortion, magnification chromatic aberration,and lateral aberration) upon focusing on infinity, of the variablemagnification optical system ZL12 according to Example 12, in which part(a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. FIG. 36 shows graphs illustrating lateral aberration of thevariable magnification optical system ZL12 according to Example 12 whenimage blur correction is performed upon focusing on infinity, in whichpart (a) illustrates the wide-angle end state, part (b) illustrates theintermediate focal length state, and part (c) illustrates the telephotoend state. In this example, the optical performance during vibrationreduction is illustrated as a lateral aberration graph corresponding toan image height of ±27.10 about the image height y=0.0 as illustrated inFIG. 36.

As is obvious from respective aberration graphs, it is understood thatthe variable magnification optical system ZL12 according to Example 12has a satisfactory optical performance such that aberrations aresatisfactorily corrected in states ranging from the wide-angle end stateto the telephoto end state. Moreover, it is understood that the variablemagnification optical system ZL12 has an excellent imaging performanceupon image blur correction.

According to the above-described examples, it is possible to implement avariable magnification optical system which has a F-value as bright asapproximately F2.8 to F3.5 and a wide angle of view of approximately 50°or more in terms of a half-angle of view, and in which aberrations arecorrected satisfactorily.

While the present invention has been described by assigning referencenumerals to elements of the embodiment for better understanding of thepresent invention, the aspect of the present invention is not limited tothis. The following content can be appropriately employed within a rangewhere the optical performance of the variable magnification opticalsystem is not diminished.

Although the numbered examples of a four-group configuration, afive-group configuration, and a seven-group configuration have beenillustrated as numbered examples of the variable magnification opticalsystem ZL, the present invention is not limited to these and can beapplied to other group configurations (for example, a six-groupconfiguration, an eight-group configuration, or the like). Specifically,a configuration in which a lens or a lens group is added at a sideclosest to the object and a configuration in which a lens or a lensgroup is added at a side closest to the image may be employed. A lensgroup having positive or negative refractive power may be added betweenthe first lens group and the second lens group. Furthermore, a lensgroup which has negative or positive refractive power and of which theposition in the direction orthogonal to the optical axis is immovablemay be added at an image-plane-side of the vibration-reduction lensgroup VR (in this case, the distance between the vibration-reductionlens group VR and the lens group which has negative or positiverefractive power and of which the position in the direction orthogonalto the optical axis is immovable may be changed or not) upon varyingmagnification. Moreover, although the fourth lens group G4 in Examples 1to 3, 5, and 7 to 11 and the sixth lens group G6 in Examples 4, 6, and12 have been illustrated as an example of the image-side lens group RPhaving the strongest positive refractive power among the lens groupshaving a positive refractive power arranged closer to the image sidethan the vibration-reduction lens group VR, the present invention is notlimited to this. The distance between lenses included in the image-sidelens group RP may be fixed upon varying magnification. A lens grouprefers to a portion having at least one lens isolated by air space whichchanges upon varying magnification or focusing.

The intermediate group is a lens group which is disposed closer to theimage side than the second lens group and is disposed at an object-sideof the vibration-reduction lens group at a position to face thevibration-reduction lens group. The aperture stop may be disposed at anobject-side of the intermediate group at a position to face theintermediate group.

Moreover, as for lenses that form the intermediate group, the positionsin the optical axis direction upon varying magnification may be changedintegrally, and the lenses may be grouped into two or more lens groups,and the distance between the lens groups may be changed upon varyingmagnification.

At least a portion of the lenses of the intermediate group may be moved(or fixed) in the optical axis direction integrally with thevibration-reduction lens group upon varying magnification.

In the variable magnification optical system ZL, a portion of a lensgroup, an entire lens group, or a plurality of lens groups may be movedin the optical axis direction as a focusing lens group in order toperform focusing from an object at infinity to an object at a closedistance. Moreover, such a focusing lens group can be applied toautofocus and is also suitable for driving based on an autofocus motor(for example, an ultrasonic motor or the like). Particularly, it ispreferable to use at least a portion of the second lens group G2 as thefocusing lens group described above.

In the variable magnification optical system ZL, an entire arbitrarylens group or a partial lens group may be moved so as to have acomponent in the direction vertical to the optical axis or may berotated (oscillated) in an in-plane direction including the optical axisso as to function as a vibration-reduction lens group VR that correctsimage blur occurring due to camera shake or the like. Particularly, itis preferable that at least a portion of an optical system disposedcloser to the image side than the intermediate group Gn which isdisposed closer to the image side than the aperture stop S and hasnegative refractive power is used as the vibration-reduction lens groupVR. Moreover, in the case of a four- or five-group configuration, it ispreferable that at least a portion of the third lens group G3 is used asthe vibration-reduction lens group VR. Moreover, in the case of aseven-group configuration, it is preferable that at least a portion ofthe fifth lens group G5 is used as the vibration-reduction lens groupVR. Furthermore, a lens of which the position in the directionorthogonal to the optical axis is fixed may be disposed at an image-sideof the vibration-reduction lens group VR, and the lens may be moved orfixed upon varying magnification integrally with the vibration-reductionlens group VR.

In the variable magnification optical system ZL, the lens surface may beformed as a spherical surface or a flat surface and may be formed as anaspherical surface. When the lens surface is a spherical surface or aflat surface, it is possible to facilitate lens processing, assembly,and adjustment and to prevent deterioration of optical performanceresulting from errors in the processing, assembly and adjustment.Moreover, deterioration of the rendering performance is little even whenthe image plane is shifted. When the lens surface is an asphericalsurface, the aspherical surface may be an aspherical surface obtained bygrinding, a glass-molded aspherical surface obtained by molding glassinto an aspherical surface, or a composite aspherical surface obtainedby forming a resin on the surface of glass into an aspherical shape.Moreover, the lens surface may be a diffraction surface and may be arefractive index distributed lens (a GRIN lens) or a plastic lens.

In the variable magnification optical system ZL, it is preferable thatan aspherical surface is formed on a lens formed of a medium in whichthe refractive index nd for the d-line is smaller than 70. The lensformed of a medium in which the refractive index nd for the d-line issmaller than 70 is preferably disposed in a lens group having thestrongest positive refractive power among the lens groups disposedcloser to the image side than the vibration-reduction lens group VR.Moreover, the lens formed of a medium in which the refractive index ndfor the d-line is smaller than 70 is more preferably disposed in a lenscomponent disposed closest or the next closest to an object, of the lensgroup having the strongest positive refractive power among the lensgroups disposed closer to the image side than the vibration-reductionlens group VR. Furthermore, an aspherical surface of the lens formed ofa medium in which the refractive index nd for the d-line is smaller than70 is more preferably a surface located closest to the object plane, ofthe lens group having the strongest positive refractive power among thelens groups disposed closer to the image side than thevibration-reduction lens group VR.

In the variable magnification optical system ZL, it is preferable thatthe aperture stop S is disposed between the second lens group and theintermediate group Gn as described above. However, the role of theaperture stop may be substituted by the frame of a lens withoutproviding a separate member as the aperture stop.

In the variable magnification optical system ZL, each lens surface maybe coated with an anti-reflection film which has high transmittance in awide wavelength region in order to decrease flare and ghosting andachieve satisfactory optical performance with high contrast.

The variable magnification ratio of the variable magnification opticalsystem ZL is approximately between 2.0 and 3.5.

EXPLANATION OF NUMERALS AND CHARACTERS

ZL (ZL1 to ZL13) Variable magnification optical system

G1 First lens group

G2 Second lens group

G3 Third lens group

G4 Fourth lens group

VR Vibration-reduction lens group

S Aperture stop

I Image plane

1 Camera (Optical apparatus)

1. A variable magnification optical system comprising: a first lensgroup having a negative refractive power; a second lens group having apositive refractive power; an intermediate group disposed closer to animage side than the second lens group; and a vibration-reduction lensgroup disposed closer to the image side than the intermediate group andconfigured to be movable so as to have a component in a directionorthogonal to an optical axis, wherein the system performs varyingmagnification by changing at least the distance between the first lensgroup and the second lens group and the distance between the second lensgroup and the intermediate group, and the system satisfies the followingconditional expression:1.500<β(Gn)t<100.000 where β(Gn)t: an imaging magnification of theintermediate group in a telephoto end state.
 2. The variablemagnification optical system according to claim 1, wherein the systemsatisfies the following conditional expression:1.360<−f(Gn˜G(VR))w/fw<5.000 where f(Gn˜G(VR))w: a composite focallength from the intermediate group Gn to the vibration-reduction lensgroup in a wide-angle end state fw: a focal length of an entire systemin the wide-angle end state.
 3. The variable magnification opticalsystem according to claim 1, wherein the system includes an image-sidelens group having the strongest positive refractive power among lensgroups which are disposed closer to the image side than thevibration-reduction lens group and have positive refractive power, thedistance between the image-side lens group and the vibration-reductionlens group changes upon varying magnification, and the system satisfiesthe following conditional expression:0.400<f(RP)/f(FP)<2.000 where f(RP): a focal length of the image-sidelens group f(FP): a composite focal length in the wide-angle end state,of lenses disposed closer to the image plane side than the first lensgroup and disposed closer to the object side than the intermediategroup.
 4. The variable magnification optical system according to claim1, wherein the intermediate group has negative refractive power and ofwhich the position in the direction orthogonal to the optical axis isfixed.
 5. The variable magnification optical system according to claim1, wherein the intermediate group has one or more positive lenscomponents and one or more negative lens components.
 6. The variablemagnification optical system according to claim 1, wherein the secondlens group includes at least four lens components.
 7. The variablemagnification optical system according to claim 1, wherein the secondlens group is constituted by, in order from the object, a 21st lensgroup having a positive refractive power and a 22nd lens group having apositive refractive power, and the 21st lens group is moved toward theimage side as a focusing lens group to perform focusing from an objectat infinity to an object at a close distance.
 8. An optical apparatushaving the variable magnification optical system of claim 1 mountedthereon.
 9. A method for manufacturing a variable magnification opticalsystem, wherein the variable magnification optical system comprising: afirst lens group having a negative refractive power; a second lens grouphaving a positive refractive power; an intermediate group disposedcloser to an image side than the second lens group; and avibration-reduction lens group disposed closer to the image side thanthe intermediate group and configured to be movable so as to have acomponent in a direction orthogonal to an optical axis, wherein thesystem performs varying magnification by changing at least the distancebetween the first lens group and the second lens group and the distancebetween the second lens group and the intermediate group, and the methodcomprising: arranging the respective lenses in a lens barrel so as tosatisfy the following conditional expression:1.500<β(Gn)t<100.000 where β(Gn)t: an imaging magnification of theintermediate group in a telephoto end state.